the build alone takes 8 hours on my core2duo/3GB system.
it will be UI-agnostic, the default gnome-mobile UI(sato?) is really unimpressive.
for wireless and router, openwrt fits well. for handheld if you dislike Android/meego you can use poky/OE. for general in-house build you can use buildroot or run-your-own. for high end embedded product you have debian/gentoo, i still failed to see the big advantage of this project, though the more the merrier.