Brian passed on this tip from Kevin Doel. Looks like Tetris is being ever-zealous in broadly defending their "look and feel" trademarks:

Phunkware's Shaker game is being pulled from the market in about 5 hours. The Tetris Company contacted Apple claiming the game is too close to Tetris for comfort.

If this is legit, and you read this post in time, and the FREE game at all interests you, walk -- don't run -- to the App Store and grab Shaker now!