Apple has published lists with the best-selling (revenue) and top-rated titles for 2009 (thus far, we assume) on AppStore. As you can see EA has a rather dominant hold on the revenue side of things while it's more varied when it comes to the top-rated games.
Top sellers 2009 (revenue):
1. The Sims 3 (EA Games)
2. The Oregon Trail (Gameloft)
3. Need for Speed Undercover (EA Games)
4. Madden NFL 10 (EA Games)
5. Tiger Woods PGA Tour (EA Games)
6. Assassin's Creed: Altair's Chronicles (Gameloft)
7. Flight Control (Firemint)
8. Cooking Mama (Taito)
9. Civilization Revolution (2K Games)
10. Wheel of Fortune (Sony Pictures)
Top-rated 2009:
1. Spider: The Secret of Bryce Manor (Tiger Style)
2. Real Racing (Firemint)
3. Zenonia (Gamevil)
4. Ravensword: The Fallen King (Gameloft)
5. Earth vs. Moon Ep. 2: Enter the Perk Shop (Low Five Games)
6. Sally's Spa (Games Cafe)
7. Ragdoll Blaster (Backflip Studios)
8. Canabalt (Semi Secret Software)
9. Blades of Fury (Gameloft)
10. Doom Classic (id Software)