According to Paul Thurott, Microsoft will launch their next OS, Windows Vista (previously known as Longhorn) in seven editions.
Windows Vista will be shipped in two main categories: Home and Business.

In the Home Category, Microsoft wants to create four editions:

Windows Vista Starter Edition, aimed at beginner computer users in emerging markets.

Windows Vista Home Basic Edition: roughly analogous to Windows XP Home Edition

Windows Vista Home Premium Edition will include everything from Home Basic, as well as Media Center and Media Center Extender functionality (including Cable Card support), DVD video authoring and HDTV support, DVD ripping support, Tablet PC functionality, Mobility Center and other mobility and presentation features, auxiliary display support, P2P ad-hoc meeting capabilities, Wi-Fi auto-config and roaming, unified parental controls that work over multiple PCs, backup to network functionality, Internet File Sharing, Offline Folders, PC-to-PC sync, Sync Manager, and support for Quattro Home Server

Windows Vista Home Premium Edition, similar to XP Media Center Edition

Windows Vista Ultimate Edition: a superset of both Vista Home Premium and Vista Pro Edition, so it includes all of the features of both of those product versions, plus adds Game Performance Tweaker with integrated gaming experiences, a Podcast creation utility (under consideration, may be cut from product), and online "Club" services and other offerings

In the Business Category, Microsoft wants to introduce three editions:

Windows Vista Professional Edition, aimed at the business consumer

Windows Vista Small Business Edition, designed for small businesses without IT staff

Windows Vista Enterprise Edition, optimized for the enterprise. Ships with Virtual PC & the multi-language user interface (MUI)

More here