This post discuss about the “backup plug-in with Exchange 2007 SP2” and “how Windows Server Backup on Windows Server 2008 does not provide any out-of-the-box functionality to backup Exchange 2007.” The backup integration will enable Windows Server Backup to backup Exchange data. Note that there is no specific "Exchange only" granularity when you are backing things up. In other words, the backup is volume-based. If Exchange data is on C: drive, backing up the C: drive will also give you an Exchange-aware backup of Storage Groups located on that drive (and purge the transaction logs from all backed up Storage Groups if backup completed successfully).[…]

More info: Exchange Team