I was actually preparing a similar post to the link below, and installing different Vista/Longhorn builds in Virtual Server, but it looks like I was beaten to it.

IntelliAdmin has a pretty cool post about the history of Vista (I guess you could call it a 'Vista-ry'  :: waits for laughter ::         :: continues to wait ::        Eh?  Aw, nevermind) throughout development.  It doesn't have anything to do with Virtualization, but you should still check it out.