For me, there are some interesting developments hidden in here... some highlights;
- Windows Live ID authentication, that can be used with Messenger, Spaces, and all of the other Windows Live services - single authentication, across many many services (not just email)
- 5 GB of mailbox quotas - this is a sign of things to come. Given that Exchange 2007 is best upto 1-2GB max.does this mean a new storage engine for Exchange finally? Will this be SQL2008 based?
- Ability to integrate on-premises Exchange deployment for faculty and staff, with hosted Exchange Labs for students - this is probably due to directory and authentication changes, but this means that companies with global offices or dispersed/mobile workforces can now choose to combine Exchange systems as the require - on-premise and hosted-service
There are also some administration features appearing too, including self-service DL management inside OWA, similar to the Window Mobile features available in OWA today. Some of that detail is here