I believe that AsbestOS (http://marcansoft.com/blog/2010/10/asbestos-running-linux-as-gameos/ http://marcansoft.com/blog/2010/10/asbestos-running-linux-as... se

I believe that AsbestOS (http://marcansoft.com/blog/2010/10/asbestos-running-linux-as-gameos/ http://marcansoft.com/blog/2010/10/asbestos-running-linux-as... seems most authoritative) is what you're looking for. It's early; you need to netboot a PPC linux kernel, but that blog post mentions pretty much everything that you need to do to get linux running in GameOS. I can't find anything about a root-key signed version of AsbestOS that allows booting without the USB hack, but I could have sworn that I had found it earlier today. Maybe somebody else can give a link?