I think its better to start off with BeagleBoard/GuruPlug/SheevaPlug and alike instead of focusing on mobilephones. There are allready a lot linux based (successfull) OSes out and have pretty good shape. I think the focues should be on "hackaway gadgets" (as BeagleBoard/...) and multi usage devices.

I would be willing (with help of some mastermind) to setup, update, keep updated a rootfs/kernel/howto for guruplug server plus.