I’ve worked on a couple of Linux devices that hook up to the cellular networks. Normally those are data only devices however, using prepackaged modules meant specifically for data only devices. However Surj Patel has been looking at making his own Linux based cell phone, and has a module that does both voice and data with minimal hookups. W00t!! Now this would be a great basis for some SuperHappyDevHouse hackery, or a Mobile Homebrew set of meetings.