The wiki has instructions for the N900! Not everything works, but it appears to be a work in progress.

This will become increasingly important as Google has boiled the frog too fast while trying to force its new store policies + banning sideloading; however, all of the pieces are now in place for them to try again in a year or 2, which history shows us they will. It’s certainly time to start toying with Linux phones if you haven’t already. This year I picked up an Xperia 10 to flash Sailfish OS on—which has rough edges (many of the hardware issues should be fixed in the next release), but Android App support bridges some of the gaps in application support.