Home Basic: Home Basic is intended for budget users not requiring advanced media support for home use. The Windows Aero theme with translucent effects will not be included with this edition. Home Basic will support up to 8 GB of physical memory. Price: 200$, upgrade: 100$
Home Premium: Containing all features from Home Basic, this edition will additionally support more advanced features aimed for the home market segment, such as HDTV support and DVD authoring. Extra games, mobile and tablet computer support, file system encryption, and a photo management application are also included. This edition is comparable to Windows XP Media Center Edition and Tablet PC Edition. Home Premium will support up to 16 GB of physical memory. Price: 240$, upgrade: 160$
Business: Comparable to Windows XP Professional, and aimed at the business market. Does not include the Media Center features of Home Premium, but does include the IIS web server, fax support, offline files, dual (physical) processor support, Remote Desktop, ad-hoc P2P collaboration capabilities, Previous Versions, and support for 128 GB of memory. Price: 300$, upgrade: 200$
Ultimate: This edition combines all the features of the Home Premium and Enterprise editions, and additionally comes with podcast creation support, a game performance tweaker (WinSAT), DVD ripping capabilities, and special online services for downloadable media, as well as additional customer service options. The Ultimate edition is aimed at high-end PC users, gamers, multimedia professionals, and PC enthusiasts. Price: 400$, upgrade: 260$
Also note the other releases will be:
Starter: Much like Windows XP Starter Edition, this edition will be limited to emerging markets such as India,Russia, Mexico, Brazil, Thailand, and Indonesia, mainly to offer a legal alternative to using unauthorized copies. It will not be available in the United States or Europe.
Enterprise: This edition is aimed at the enterprise segment of the market, and is a superset of the Business edition. Additional features include multilingual user interface support, BitLocker Drive Encryption, and UNIX application support. This edition will not be available through retail or OEM channels, but through Microsoft Software Assurance.
I have the luck of my University offering the Ultimate edition free to certain majors, one of which, I am. So i don't need to drop the hefty 400$ pricetag for it.