Dunkin! (I'm almost as happy to see you as Paul Atreides)
I think MC will let you alter tags before you rip them. As Jim said, setting the Album Artist tag to a single value for compilation albums will allow MC to group that album together all as one. For compilations with lots of unrelated artists, many people use:
Various Artists
(Multiple Artists)
That second one is used commonly because it makes them sort at the beginning of an alphabetical listing because of the parenthesis. For other albums where there are simply a few guest artists, or something like that, Album Artist usually gets set to the main artist's name.
Here's a wiki entry that explains this in some detail:
http://wiki.jriver.com/index.php/Album_Artist_and_Album_Artist_(Auto)
Even if MC doesn't let you enter this field before ripping a CD, you can absolutely change it after the fact by using MC's Tagging Window. Just select the files and Edit > Tag . Then set the Album Artist tag and you're all set.
Brian (who knows the Weirding Way of MC).