The Windows 7 build delivered to developers at PDC 2008 has generated quite a few questions about what exactly is contained in the Enterprise edition that are not in the other editions. I'd like to point out that the final lineup of editions has yet to be finalized, but we know for a fact that there will be an Enterprise edition that is a benefit of customers that purchase Software Assurance for their Windows machines. This edition has some very nifty features, indeed, listed here: http://www.microsoft.com/windows/products/windowsvista/enterprise/windows7.mspx
Note that each of these features are very popular discussions at all of the large companies I help:
DirectAccess keeps mobile users connected on the go
BranchCache makes file access faster
Search information on the PC, mail or SharePoint
BitLocker protects data on a PC and portable drives
AppLocker lets you control what user's can run
Virtual Desktop Infrastructure made better
Management tools to improve IT productivity
Compatibility with Windows Vista and ease of deployment