Exchange 2007 Documentation

I know a couple of books have been put out on Exchange 2007 already, such as:

• Microsoft Exchange Server 2007 Unleashed by Rand Morimoto, Michael Noel, Andrew Abbate, and Chris Amaris (Paperback - Jan 23, 2007)
• Microsoft Exchange Server 2007 Administrator's Pocket Consultant (Pro Administrator's Pocket Consultant) by William R. Stanek (Paperback - Jan 31, 2007)

I intend to get my copy of these books soon. However, in the meantime the premier source of documentation and reading material comes from Microsoft directly on the TechNet website:

http://technet.microsoft.com/en-us/library/aa996058.aspx

This, of course, includes documentation on Exchange 2003 as well.

Personally, I have used the TechNet documentation extensively in preparing and planning for a migration to 2007. I feel that it's a great place to start if you're looking to just dig in and do some solid reading on the product. Check it out and I think you'll agree!