The official website has now comments to all games from the first three rounds.
1. Aronian - Carlsen
In the second game Carlsen, being behind in the score played the Volga gambit, as expected. In game four, since he has equalised, I think he is not going to repeat this experiment, but return to his usual Nimzo or Queen's Indian.
2. Gurevich - Leko
Leko played a nice game in the Classical Nimzo-Indian and won with Black. Since Gurevich is already two points behind, I think he is going to play 1.c4 in game four, to avoid Leko's excellent preparation.
3. Rublevsky - Ponomariov
In game two, Rublevsky played 6.Bc4 against Ponomariov's Najdorf. Ponomariov had no problems and even had the better chances in the game, which ended in a draw. Since Rublevsky won game three and is in the lead, I think he will return to his usual 3.Bb5+. Ponomariov will repeat the Najdorf, because he needs a win.
4. Kasimdzhanov - Gelfand
In game two Kasimdzhanov tried Gelfand's Queen's Indian, but it was a draw after only 23 moves. I think in game four Kasimdzhanov will test Gelfand's Petroff.
5. Bacrot - Kamsky
Kamsky surprised Bacrot with the Dutch. His strategy to surprise Bacrot in the opening while avoiding theoretical discussions has worked very well so far. Being to points in the lead I think he will play another surprise opening instead of his usual Slav, but something more solid. Maybe the Queen's gambit accepted?
6. Malakhov - Grischuk
Malakhov came close to defeating Grischuk in game two with 1.c4, so I think that is what he will try again.
7. Bareev - Polgar
Bareev beat Polgar in the topical Queen's Indian line with 1.d4 Nf6 2.c4 e6 3.Nf3 b6 4.g3 Ba6 5.Qc2 c5 6.d5. Polgar is one point behind, and has two Black games remaining, with only one White, so may it already be time to bring back the King's Indian?
Bareev likes to play the Averbakh system against the King's Indian (1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Be2 O-O 6.Bg5).
They have played already a few games in this line against each other, but that was a decade ago or more, when the King's Indian was at the height of its popularity.
8. Shirov - Adams
In games two and three a theoretical discussion about the New Archangel line of the Spanish took place: 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O b5 6.Bb3 Bc5. After 7.a4 Rb8 8.c3, Adams with Black in game two played 8..O-O, and Shirov with Black in game three chose the main line with 8..d6. I don't know if Adams is going to continue this discussion, or play the Marshall instead.