Just came out, download away and start your testing...
Read the Exchange Team Blog SP2 categories here http://blogs.technet.com/exchange/archive/category/10058.aspx
Read about Exchange Server 2003 Support for Mobile Devices http://www.microsoft.com/exchange/evaluation/features/owa_mobile.mspx
Exchange 2003 SP2 Overview
New for mobility is direct push, which is an Exchange technology that maintains an open connection between the mobile device and the server. Remote wipe is another new feature, and it enables administrators to delete sensitive data from a lost or stolen mobile device. Other features include global address list (GAL) lookup, policy provisioning whereby administrators can make supported policies more secure, support for certificate-based authentication, use of S/MIME to sign and encrypt mail, and server-based synchronization of Tasks.
Anti-spam improvements are included in the release of the integrated version 2 of Microsoft Exchange Intelligent Message Filter, and Sender ID, which is an industry-standard framework. Version 2 of Intelligent Message Filter contains significant improvements in the anti-spam area for SP2.
For Exchange Server 2003 Standard Edition, the hard-coded licensing database size limit has been increased from 16 GB to 75 GB. The administrator can set a protective database size limit (prevent unintentional database size growth). The default value will be 18 GB in SP2 for Standard Edition and the default can be changed.
Public folders are now more manageable. Administrators can now track who deleted public folders, stop and resume public folder replication, synchronize the public folder hierarchy, propagate access control list (ACL) changes through public folder hierarchy, and propagate replica list changes through the public hierarchy. Many of the improvements work toward minimizing the effect of replication storms.
There is a new version of the offline address book (OAB 4.0) that features the reduction in the OAB size, differential OAB update files, indexing based on locale setting, and improved diagnostic logging.