Exchange SP2 has left the building.
It contains some interesting features. The one I like the most is Address Book Policies. With ABP the administrator can easily configure which users can see which Address Book/s. This gives the function that many organizations want to segment address book for users in a supported way instead of the really messy solution by ACL'ing different objects in Exchange.
Other feature is for example the good old OMA is back. It's like OWA but without graphics and probably most used by mobile devices. The official name is 'OWA Mini'.
For you people that want configure your on-premise Exchange installation with O365 in hybrid configuration there is the new 'Hybrid Configuration Wizard' that help you setup the configuration a lot easier than the myriads of manual steps needed before.
Pre-requirement info http://technet.microsoft.com/en-us/library/bb691354.aspx
Release notes http://go.microsoft.com/fwlink/?LinkId=235234