Getting TileMill up on Ubuntu 11.10 is pretty straightforward following the directions on building from source. The only snags seem to be that the one-line install for npm didn’t work and I had to grab the repo and follow the readme to get it moving.
A couple minor hiccups:
I did run into a couple odd quirks on the install and had to delete and add TileMill itself a second time. Be careful on sqlite versions as well.
The MapBox directory actually gets dumped in home/[user]/Documents/MapBox, not /usr/local/shared, per documentation.