Letterpress by Atebits
From Loren Brichter, who brought you the best Twitter client that Twiter bought and destroyed, comes a word puzzle game?
Find words, steal tiles, color the board! Letterpress is a fresh new word game for iPhone, iPad, and iPod touch. Play with your friends using Game Center! The perfect blend of fun and strategy.
Screenshots of Letterpress permalink
It's available for free in the App Store with an in game purchase option that, according to this review at Macstories, unlocks:
Specifically, a $0.99 in-app purchase will let you play more than two games at the same time, it’ll unlock themes, and it’ll allow you to see played words during a game.
You'll need a friend to play with as it's multiplayer only. There's an auto-match feature in game to try and pair you with someone else.