[bchen]

This is slightly off topic, but make sure you are on the latest version of Parallels before doing the upgrade. For some reason, Parallels 6, which is less than 2 years old, does not support Mountain Lion. Personally, I do not care about the new features in Parallels 7, but was a bit annoyed when forced to upgrade.

[adestefan]

I got bit by the same thing with VMware. You must be on Fusion 4 for Mountain Lion. Sucks because I had no plans on upgrading.

[jasomill]

There's a free Technology Preview of Fusion 5 that's time-limited, but probably not so much that it wouldn't work until Fusion 5 ships. Mountain Lion is officially supported as a host and guest. I've been using it daily for a couple months to run Windows (7 and Server 2008 R2, plus the various previews of 8 and Server 2012), FreeBSD, and OS X (Lion, Snow Leopard Server, and Leopard Server), and it seems stable.

[rogerchucker]

I was surprised to see myself being forced to upgrade to the next version of Parallels. Pretty annoying.