Replicant

I have froyo running on the freerunner and it certainly is not as fast as one may have the experience from a newer smart phone, though it is certainly reasonably fast enough to work with it.
the guys from the androind-on-freerunner (aof) project are doing a great job and it is constantly improving in speed. armv4 is certainly a big hurdle though maybe the aof guys are able to help or maybe this could even be a joint project to backport the important apks to armv4. If I remember correctly they have some strategy on how to develop also for newer android versions without always having to start from scratch.