One of my favorite games, World of Goo, has been released for the iPhone. It's the king of physics puzzlers and now, it's on the iPhone and iPod Touch.
You may remember how excited I was when the iPad version was finally released. 2DBoy prioritized that version over the iPhone version, and the app really shines on the iPad. The iPad was the third platform I played through the game on, and the touch interactions really make the app shine.
Those interactions are now on the iPhone and I can finally take the balls of goo with me!
By the way -- already bought the iPad version of World of Goo, no worries, there's an update available now that makes it a Universal app and will now work on your iPhone or iPod Touch.