Instead of hammering up Maemo 5 and all the old closed source bits inside it, why not take MeeGo DE (the core runs fine, handset UX however does not) and put Hildon on top of it? Due to QT and python, it'd be easy to fix up and port them to a system with: patched up and improved Hildon, armv7-hardfp+neon, 2.6.37+drivers (BTRFS!), newer Python packages (think Python 3+) that don't break the system, a close-to-upstream system, and according to smoku, possibly: GTK3.

Downsides:
EVERY MAEMO APP will need to be recompiled.Easy Debian images will need to be rebuilt for hardfp.Oh, did I mention that everything will need to be repackaged in RPM?