Sicilian players, what do you do against Bc4?

I notice alot of white players play an early Bc4 (as their second or third move).  Supposedly this is "supposed to" be bad, but what can you really do against it?

I like to play a6, and subsequently b5 with tempo. 

Here is a game I played against it.

http://www.chess.com/echess/game.html?id=6486821

well, here is some analysis by fritz

Many "Patzer"s (=beginners in chess) play 2. Bc4. It looks naive, since black has not yet weakened f7, by playing e7-e5 - as in openings starting with 1. e4 e5.

Black should gain a tempo by driving back the bishop with e6 and then d5.

(see the Fritz analysis).

However, the bishop is not placed so badly on b3 (or a2), since he can put pressure on the black centre. If black plays uncautiously Bf8-c5 or Bf8-d6 later then that pressure can become annoying after Bg5... (here, d5-d4 is often not a good option, since this makes the Bb3(a2) alive again!).

It is more precise to hinder this plan of white by playing Be7, or first h7-h6, and then Bd6 ( or even Bc5).  

In such a case, white often needs to find a new prospective for his Bb3(a2), by playing c2-c3, and then Bc2(b1). This is not so terrible for black. 

So if black takes care of d5, white does not have any advantage. 

My conclusion is: 1.e4 c5 2. Bc4 is perfectly playable for white , since it has a positional basis . But black equalizes earlier  than in other systems of the Sicilian. 

Mandelshtam 

As has been stated, Black can equalize fairly easily in many lines with an early Bc4, but that's still a long way from getting an advantage. If you got a decisive advantage against it early on, that simply means your opponent did indeed play on beginner level.

The point is that you still have to pay some attention to move order issues, because White can still transpose into Open Sicilian main lines you may not be familiar with, an example: If after the sequence 1.e4 c5 2.Nf3 Nc6 3.Bc4 you go for the d5 break by playing 3...e6, White's 4.d4 gets you into some Poulsen, Sozin or Scheveningen lines of the open Sicilian. This is still OK for Black, but it can throw you off balance if you usually would play the Dragon (lines with g7-g6) or the Sveshnikov (involving an early e7-e5, but you wouldn't want to try that against an early Bc4 anyways). So, as a Dragon player, 3...g6 would obviously the move, and later you will have to decide whether Nf6 or e6 and Nge7 is the correct setup. When doing so, always consider the consequences of White playing a delayed d2-d4!