Microsoft detailed the versions Windows 7 will be available in. There are 5 Windows 7 editions on the market. This sounds worse than it really is. For most users it will either be Windows 7 Home Premium or Windows 7 Professional.
Windows 7 Enterprise is for volume license and Windows 7 Ultimate is only going to be available in limited quantities for those that always need everything available. There is also a Windows 7 Starter edition, but that is only for emerging markets.
What was also revealed is that XP users will need to do a clean install if they want to upgrade to Windows 7. There are supposedly some tools that will help with the data migration. This sounds like a pain.
More details on the different Windows 7 SKUs can be found on WinSuperSite.