The Exchange Team has blogged about the upcoming SP2 for Exchange 2007.

SP2 will make it possible to deploy Exchange 2010 in an existing 2007 organization (yes, you really have to wait for SP2 to be able to do that!). But even without the coexistence scenario it still contains some very interesting features, especially the long awaited Exchange Volume Snapshot Backup Functionality which makes it possible to do a snapshot backup without any third party application. SP2's ETA is third quarter of 2009.

Read all about it at: http://msexchangeteam.com/archive/2009/05/11/451281.aspx, more details at http://blogs.technet.com/scottschnoll/archive/2009/05/12/exchange-server-2007-sp2-and-backups.aspx