I've successfully installed and ran Android on my N810 following the instructions here along with the modifications described here. In the next days/weeks I'll have a deeper look at it and will also try to install some more apps.
There is another project (involving the same people?) called NITdroid, which allows to run Android directly, bypassing Maemo. However my understanding is that short of reflashing the kernel there is no easy way to switch between Maemo and Android (with the first method you only have to reboot to get back to Maemo after using Android). There are discussion here and there about using kexec to swich between Maemo and Android but so far I'm not aware of anybody getting kexec to work on a NIT.