I have tried 4. ... e6 against the Panov Botvinnik quite a few times in blitz game and it does tend to end up with a position I'm happy with. However the statistics on 365chess.com suggest that White wins about 50% of the games and Black only 25%. The numbers are much closer with 4. ... Nf6
http://www.365chess.com/opening.php?m=8&n=94&ms=e4.c6.d4.d5.exd5.cxd5.c4&ns=3.31.21.32.93.99.94
In my game - I was quite surprised by 6. h3 but it has been played before and I think I can see the reasoning behind it: Black has one obvious square to develop his light-squared bishop, namely g4 (probably after Nf3 by White). He can also play the more surprising Be6 in some lines, but this is generally only good if White has played Bg5, meaning an immediate Ng5 isn't possible. I believe the idea behind 6. h3 is that White intends to prevent Bg4 and then discourage Be6 by not playing Bg5. Of course Black can always leave his bishop on c8, which is better than you might think.
Whilst I welcome all comments, I'm afraid that I can't take seriously sundown316's statement that the Panov Botvinnik attack is "an over-rated piece of rubbish". This is an opening that has been used to defeat the likes of Euwe, Botvinnik and Karpov! Like almost every opening and defence which has earned a name, it is certainly playable at my level (my opponent in the game I posted is ~1900 FIDE and I'm ~2100)
Anyway, I'd like to end with this game, which I found amusing for various reasons:
[Event "New York op"]
[Site "New York"]
[Date "1992.??.??"]
[Round "2"]
[White "Hoyos Millan, Luis Bernardo"]
[Black "Schrade, T"]
[Result "1-0"]
[WhiteElo "2215"]
[BlackElo "0"]
[ECO "B13"]
[PlyCount "35"]
1.e4 c6 2.d4 d5 3.exd5 cxd5 4.c4 Nf6 5.Nc3 Nc6 6.Nf3 Bg4 7.cxd5 Nxd5 8.Qb3 Bxf3 9.gxf3 Nb6 10.Be3 e6 11.Rd1 Be7 12.d5 exd5 13.Nxd5 Nxd5 14.Rxd5 Qc7 15.Bb5 O-O 16.O-O a6 17.Bd3 Rfd8 18.Bb6 1-0