The app itself is free and includes a copy of Pong. You can pick up four-packs of games as an in-app purchase for $1.29 a pop, or spring for all 100 for $17.99.
Many of the titles support Bluetooth multiplayer, as well, provided another player has a copy of the game. (And an iPhone or iPod touch, of course.)
It all looks like a very nice package and it’s full of genuine classics like Yar’s Revenge and Battlezone, as well as more obscure titles like Sentinel and Math Gran Prix from both arcade and Atari 2600 versions. There’s even a gallery bundled in with cabinet art and manuals.
For those worried that a touchscreen system wouldn’t offer the fidelity of a real joystick, Touch Arcade points out that the Atari Greatest Hits pack should work perfectly with the iPad-based iCade home cabinet as it was designed in partnership with Atari. (They also have a list of all 100 titles.) [iTunes]