I upgraded both the player and the VMTools to the latest versions (as of July 3 2010) and noticed that Unity option is greyed out.
Unity was working great in 2.5
My guest and host OS is Vista
I also tried this with a Windows 7 host and the Vista Guset with the same results.
I also have noticed that I now no longer have a 'Windows Sleep' mode in the Vista guest, but I will put this in a different thread to keep the issues seperate.