Windows 7 Professional

The Professional edition of Windows 7 brings along more security and networking features like the Encrypting File System, advanced network backup and joining managed networks with Domain Join. Also, the Pro version brings location aware printing - whether at home or work.

Windows 7 Enterprise and Windows 7 Ultimate

Whether you're a home user or a business, the Enterprise and Ultimate editions (probably differentiated by price in the end) will bring a similar set of advanced features like for internal and external drives, DirectAccess for corporate networking based on Windows Server 2008 R2 and lock unauthorized software from running with AppLocker.

My guess is that Microsoft will market aggressively the Home Premium and Professional editions for home users while netbook users should aim for the Starter version. Microsoft also recommends business users to use either the Professional or the Enterprise edition.