So far I'm able to get 12.10 working on Parallels with some minor issues.

Minor issue #1: after install the Parallels machine did not cleanly shut down. Had to reboot VM manually.

Minor issue #2: instead of the expected /media/Parallels Tools/ , the parallels tools virtual cd-rom loaded on /run/media/Parallels Tools, and then errored out instead of installing parallels tools.

I'm surprised that these are the only issues I've run into thus far, considering how new this alpha is.