For those still unaware, the 530Mb+ file (1,4 GB extracted) contains the full set of binaries; you can use it to upgrade existing RTM or SP1 installations or deploy new Exchange 2010 SP2 installations.
Besides the usual set of hotfixes, SP2 introduces the following features:
Address Book Policies
Address Book Policies, also known as GAL segmentation, ABPs are meant to segmentize the address book, giving users a certain view of the address book like Address List Segregation did for Exchange 2003/2007.
This will be a lightweight browser like OMA in the past, meant for simple browsers.
This wizard is to make the configuration of an on-premise Exchange and Office 365/Exchange Online more simple, reducing the steps required from 49 to 6.
OWA Cross-Site redirection
This will allow clients to be silently redirected to the proper site if they log on to a CAS server located in a site different than the site where their mailbox is hosted and externalURL has been specified there.
After preparing your forest for Exchange 2010 SP2, the schema version number will have changed. Check the Schema Versions page for information on the new ObjectVersion and RangeUpper values for Exchange 2010 SP2.
Note that SP2 introduces an additional requirement, which is the IIS 6 WMI Compatibility feature; you can add this feature using the GUI or by using the Powershell cmdlets Import-Module ServerManager followed by Add-WindowsFeature Web-WMI.
The proper method to upgrade mailbox servers that are a member of a Database Availability Group is described here.
The releases notes are not available at time of writing; we’ll update this post when they become available.