Windows Starter 2007 - Vista without Aero, probably meant for developing nations.
Windows Vista Home Basic - Basic Windows Vista for your single PC fam, doesn't sound like much going on here. Analagous to XP Home.
Windows Vista Home Basic N - European version of the same, but without Media Player (because of antitrust rulings against MS in the EU).
Windows Vista Home Premium - This is the one we're all probably gonna own. It's got Media Center functionality, Cable Card support, the whole home-media shebang.
Windows Vista Business - Think of it as XP Pro, but Vista.
Windows Vista Business N - Think of it as XP Pro, but Vista, but Euro.
Windows Vista Enterprise - Business version of Vista with numerous enterprise features, like Virtual PC, volume encryption, etc.
Windows Vista Ultimate - Love that name. This one does all of the above (and more); what else do you need to know? It's ultimate Windows..