I don't own an opening database but I know 9.dxc5 is a known line, I'm just wondering if this gambit has been played before. I think it's sound, I can't find an easy way for Black to equalise.  

Only one game found in my trusty mega database - a blind blitz game =/.  Your 8... Qb6 line is quite unpopular by the way.

(scores are for white)

8... Qc7 scores 53.8% in 40 games, and has been used by at least 4 GMs most recently in 2008.

8... b6 scores 58.3% in 36 games, and has been used by at least 4 GMs, and was most recently used in 2008.

8... Nc6 has been played 10 times, by one GM (Legky - 2485 elo) in 2002.

8... Qa5 has been played 7 times, and by two GMs, most recently in 2006.

8... Qb6 has been played 3 times, once by a GM in 1985 in a blind blitz game.

Just curious: What's 7... Kf8 for?

Thanks guys

I think it is because white can play Bh6...Am I right?

 No, it's perfectly ok for black to castle. Bh6 is meet by Nf5 and white has nothing better to do than move his bishop back. So it's a bit of a waste of a move. The idea behind Kf8 is to avoid the main Qc7 line and be a little safer than castling.The down side is obviously the rook is stuck on h8 for a while.