Release higlights:

• Support for Quad-Core AMD Opteron 8300 and 2300 series processor families (codename Barcelona)
• Support for Dual-Core Intel Xeon 5200 series processors (codename Wolfdale)
• Enhanced patch management
• Support for new / updated guest OS; Windows 2003 R2 Data Center Edition and Red Hat Enterprise 5.1
• Update for service console from RHEL3 U8 to RHEL3 U9

http://www.vmware.com/support/vi3/doc/releasenotes_esx303.html#resolvedissues