Black can play the Tarrasch against the Queen's Gambit. 1.d4 d5 2.c4 e6 3.Nc3 c5. This is exactly the same position as the Panov-Botvinnik, except black gets an extra tempo (and uses it to play ...Nc6 for free). This opening is "fine" in some sense for black.
What? I assume, given your title, that I'm misunderstanding something here...
What you mean when you say the Tarrasch is exactly the same position as the Panov.
Just for reference's sake...
Thanks Conzipe for answering JonArgyle's question.
To your last comment: is it any different from playing the Caro-Kann as black? Easier? Harder?
It pays off immensely to study IQP positions so that one is not afraid of them. This, I'm guessing, is why your opponents recaptured with the piece.
As far as I was led to believe IQP positions are strong as long as there are a few minor pieces each, preferably 4; you get the e and c files for rooks also.
One specific difference between Tarrasch and Panov is that in Tarrasch white's most promissing setup is usually considered to be Rubinstein's g3 but in Panov playing g6 means a pawn sacrifice due to white's extra tempo.
I've always found it funny that in the following position 4... dxc4?! appears to be a complete patzer move - after all it surrenders centre and looses a tempo for nothing. Nevertheless it leads to the mainline of the QGA! Does that make QGA unsound?
Well, I've toyed with QGA from time to time in my own games and don't think that it's unsound. I rather believe that 4. e3 by white is such a passive move that black can do better than in QGA. If white plays more agressively black needs to make some sort of concession sooner or late an by making it at move 2 he hopes to have easy development later on.
I have done quite well with QGA but probably largely due to the fact that I've mostly played it in blitz or against weaker opponents who have not had very good idea how to proceed with white. If white knows what he is doing many of the arising isolated pawn positions require extremely carefull defending by black which isn't easy (see for example Kramnik's white games against Anand). Additionaly, there is of course the "small" matter of 3. e4!?
Smyslov was 50, Karpov was 20, and Smyslov was just 13 years removed from his world championship.
10...Nf6 // interesting - I think the main move today is ...Bf6. But ...Nf6 is not bad.
Wonderful game. You know what would be cool? A database with a small number of representative games on IQP. Famous games. This one qualifies.
It might be worth mentioning that already 13... Rc8? in Smyslov-Karpov above is probably a mistake due to 14. d5! and black is in trouble (the idea is 14... exd5 15. Bg5 g6 16. Rxe7+/-)
tempos matter everywhere
Well they matter everywhere, but sometimes they matter a lot less. One can give up a move in some positions and it will be a minor inconvenience, whereas in others it will turn a holdable position into a lost position.
What about waiting moves? Some positions are advantageous for white if it is blacks turn to move - perhaps this is a similar situation.
There are lines in some openings including the French defense that include waiting moves for black forcing white to commit to a line of play, in fact the Caro-Kan advance variation can lead to a position (if black plays c5) exactly like a French defense minus 1 tempo.
The French waiting move, I believe, is ...Be7.
1.e4 e6 2.d4 d5 3.Nd2 Be7
I can't think of any other opening which has a waiting move that early. Also, to be fair, it's not like 3...Be7 isn't a good move for black. It's not like he's playing 3...a6 or 3...c6.
The minus tempo in the C-K advance leads to a completely different position, so that's not really a good example.
@NM ozzie_c_cobblepot yes the Tarracsh variation, this video shows waiting moves at 06:37
http://www.youtube.com/watch?v=Ha2o-MoSf1M&feature=relmfu
and also the advance variation with Bd7 at 03:15
That's funny - one of the waiting moves he discussed was in fact 3...a6. (Also 3...h6).
I don't think of ...Bd7 in the French Advance as a waiting move as much, perhaps it would be better classified as a more accurate move order, or more flexible. Because in the ...Qb6 lines, black often ends up playing ...Bd7 anyways.
Ah, a chance for some fastidious positional analysis 
Although both openings could reach a similar position, there is still a fight in the opening to be done! In the panov, white is putting pressure on d5, which compels black to force the issue. In the QGA, black has no pressure to face on his center -- I think that's why he can play moves like ...a6 even with a semi-open position, because the only way white can crack things open to even attempt to get to black and "punish him" is with d5 (or else dxc5, but this is likely to totally free black's pieces), but since black has no weaknesses and many exchanges would ensue it needs a lot of preparation to become dangerous. Anyway, with this in mind, black shouldn't feel the need to play ...cxd4, opening white's bishop in the case of exd4, for a long time! In fact, black should try to make a point out of torturing white by not "capturing already!" Instead black plays ...a6, ...b5, develops actively, and takes his sweet time before committing into that pawn structure, if he does at all; he will only go into it when he feels it's favorable or necessary.
So, perhaps tempi isn't so important in the QGA 
; flexibility and freedom seem to be a good substitute. I must admit, when I first saw a strong player (I say strong because he was using a computer, which is hard to beat) play ...a6 against me in the QGA, I thought it had to be wrong, and was very surprised to see it was the main line! It seemed weird to me that black would give up the center, then wait and take pride in kicking my bishop with ...b5 above all other concerns.
And yes, I think you should give the QGA a shot; I've recently switched to it and I've really enjoyed the freedom you get with it compared to the QGD. Your pieces are a lot more active, and the only thing is you have to watch out for white's center advancing (especially in the 3 e4 variation), but black's formation is sound enough to react to it very well as long as you handle it correctly.
To me tempo is very critical in the QGA. It is because I have specific plan or objective or position to catch.
You're right that there is less pressure for Black in the QGA. It's somekind of theoretical draw of chess game.
I just decided to drop my QGA repertoire today because:
1) Most of my opponents do not follow d4 with c4, so I rarely get the QGA through 1.d4 d5 2.Nf3 move order. I just studied the Nimzo and checked the possibility to get to "QGA" through 1.d4 Nf6 2.c4 e6 3.Nf3 d5, but after comparing with QID (3...b6), I dropped it.
2) The main reason is because with QGA I didn't learn anything. With Nimzo/QID combo there are many positional aspects to be learnt. I prefer getting into trouble due to lack of opening preparation (many different variations!) but learn something than getting into trouble later on due to lack of knowledge.
Something's been bothering me for awhile.
White can play the Panov-Botvinnik against the Caro-Kann: 1.e4 c6 2.d4 d5 3.exd5 cxd5 4.c4, and black typically does not play ...dxc4 without white first playing Bd3. In some of the main lines, an extra tempo in the early middlegame is extremely important.
Black can play the Tarrasch against the Queen's Gambit. 1.d4 d5 2.c4 e6 3.Nc3 c5. This is exactly the same position as the Panov-Botvinnik, except black gets an extra tempo (and uses it to play ...Nc6 for free). This opening is "fine" in some sense for black.
Then there's the QGA, which [I believe] has a drawish reputation. But it's very similar to the Panov, except black plays ...dxc4 without waiting for white's Bd3, which in the P-B is a no-no. 1.d4 d5 2.c4 dxc4 3.Nf3 Nf6 4.e3 e6 5.Bxc4 c5 6.o-o. If black chooses at this point the third-most-popular move of 6...cxd4 then it directly transposes to what one would expect in a Panov with white a tempo up. Of course black typically plays ...a6. Is the lack of the release of tension by black with ...cxd4 and exd4 really that much better for white? Does the tempo matter?
What is the relationship between the QGA and the Panov (and the Tarrasch)?
And perhaps most relevant to myself - should I take up the QGA? I'm always looking for new drawish openings to spring on my white opponents.