The official Scrabble game for iPhone is a pretty full-featured version similar to the Mac and PC Scrabble games. There is also one for the iPod, but this version plays much better with the touch screen.
You can play against a friend on a single iPhone, or play against a computer opponent. One problem is the computer AI is too each on the medium setting, and too hard on the hard setting. There should be more settings in between, like the Mac game.
This game is a must-have if you are Scrabble fan. It is quick and easy to play a game and your Scrabble vocabulary will grow by playing it.
Read more about Scrabble and view it at the iTunes App Store.