I have been searching the web and have yet to find an answer, so I thought I would ask for a canonical answer here. Will Maemo5 and its cool new interface run on The N8x0 series devices?
Maemo 5 comes today as an SDK only since it targets the OMAP3 architecture and no OMAP2 compatibility will be officially provided. The revamped UI relying on graphics acceleration and the new functionality built around the new supported hardware made it too complex to keep the compatibility between both architectures.
This early release comes with an invitation to build variants based on Maemo 5 compatible with existing hardware like the N800 and N810. Maemo SW can't promise commercial quality for such configurations but through maemo.org we are able to collaborate at a community level with technical support, license changes and code.