The 10.6.8 update is recommended for all servers currently running Snow Leopard Server. This update includes general operating system fixes, as well as specific fixes for:
properly displaying videos in Wiki pages when viewed from Firefox or Internet Explorer browsers
reliability of using sharepoints with Time Machine
reliability of vacation mail notices
improved reliability of processing international character encodings in iCal Server
improved authentication support when accessing iCal Server from iOS devices
properly enabling previous updates in Software Update Server
improved reliability for cascading Software Update Servers

System Requirements
Mac OS X Server 10.6.7