You can now download Exchange Server 2007 Service Pack 2 from here Exchange Server 2007 SP2
We can refer to the following links to know more about SP2 in details:
- What's New in Exchange Server 2007 SP2
- Announcing the release of Service Pack 2 for Exchange Server 2007!
Things which would be of interest for Exchange application developers are:
Exchange Server 2007 Service Pack 2 (SP2), the Manage Diagnostic Logging Properties wizard is added to the Exchange Management Console. In Exchange Server 2007 Service Pack 1 or an earlier version, you must use the Exchange Management Shell to change diagnostic logging levels. for further reading Diagnostic Logging of Exchange Processes