What ConfigMgr 2007 SP1 officially contains - i.e., why upgrade
1. Complete support for management of Windows Vista SP1 and Windows Server 2008.
2. Support for Configuration Manager 2007 Server Site roles on Server 2008.
3. Integration with Intel VPro technologies.
4. Asset Intelligence 1.5
For the complete list...
http://technet.microsoft.com/en-us/library/cc161901.aspx