id Software head John Carmack has at least one very important trait in common with gangsta rap star (and gaming magnate) Ice-T: he's really fun to follow on Twitter. When he's not dropping enigmatic missives like, "Closed myself in a 1600 gallon tank for an hour. CO2 rose to 3430 ppm, humidity rose to 71%. No discomfort," he's giving his followers a taste of news before it hits anywhere else. "Rage mobile has been approved," he let his followers know this morning. "It should be on the App Store tomorrow morning!"

Rather than directly port the forthcoming FPS, Rage: Mutant Bash TV is an on-rails shooter set in the world of Rage. No price has been set for the game, but id's most expensive iPhone game to date has been the $7 Doom: Resurrection -- another on-rails shooter.

This article was originally published on Joystiq.