It took me forever to get around to watching this but this is just a great presentation about Exchange development’s future at PDC. He does a great job of explaining where we’ve been as well…
Learn about the Exchange Web Services Managed API and how Exchange is getting “Cloud Ready” at PDC’08
This is an absolute must watch for any Exchange developer!
The MAPI docs have been revamped and moved from Exchange to Outlook 2007 in MSDN. As Thom points out - they did great work on these updated docs. Steve also has a post about this along with an overview. If you are interested in MAPI, go check them out!