Recent firmware updates may have aimed to shut down such shenanigans, but it looks they were a little too slow to stop Jay Freeman (a.k.a. Saurik) from going to town with his newly jailbroken G1 and installing Debian on the handset. What's more, he apparently even managed to get Debian and Android to play nice with each other, letting you have a completely normal and unassuming phone by day and a nerd machine by night.
As you might expect, however, it's not exactly as simple as installing an app from the Android Market, but anyone with a little experience in installing Linux distributions on unconventional devices should be able to follow the instructions fairly easily, although actually turning it into something useful is another matter. Hit up the read link below to get started.