Coworker Elan Shudnow
pointed out a glaring omission with Windows Server Backup in Server 2008 - it isn't Exchange aware. In fact, many features you might have been used to in NTBACKUP are gone with the new backup program provided with Server 2008. Even if you didn't like NTBACKUP, I have a bad feeling you will like Windows Server Backup even less.
Thankfully you can use DPM or some other type of backup software for Exchange, but those aren't free.
Update: Karl Foley has a clever workaround that involves copying NTBACKUP from an XP machine and a few other Exchange-specific DLLs to make it work under Windows 2008.