The iCade is finally leaving the ThinkGeek store and is being resold at various online stores as well as brick and mortars like GameStop. Hopefully 8/16bit console emulators will take note and add iCade support soon. I'm looking at you Robert Broglia... :-)
This is the v1.7.0 iMAME4all build by David Valdeita (Seleuco). It is the first non-beta version of iMAME4all with iON's iCade support. 1.7.1 was released just hours after this video was uploaded so it's likely a newer version exists as you read this.
Games demo'd in this video in order of appearance: Pac-Man, 1942, Donkey Kong Jr, Gun.Smoke, Gyruss, Lady Bug, Millipede, Mappy, Mr. Do!, Ms Pac-Man, Q*Bert, Satan's Hollow, Time Pilot, Zaxxon, Aero Fighters 2, Asteroids, Bad Dudes, Bezerk, Captain Commando, Defender, Gauntlet, Ghost'n Goblins, Joust, Karate Champ, MegaMan the Power Battle, Metal Slug 2, Street Fighter 2, Wizard of Wor, Strider (kind of).
...yes, you have to jailbreak your iPad to install iMAME4all. As of this writing, I believe the Atari's Greatest Hits app is the only iCade compatible game at the Apple AppStore.