I organise them in directories, so have a separate set for Various artist albums. I don't expect every music player to support an "Album artist" tag though. If you're a classical music enthusiast, no doubt you'd insist that you can't organise your music without "Composer" and "Conductor" tags.

Personally, I prefer things as they are in the N900 - if I browse by artist then I want to see all artists, that's the whole point of browsing by artist.