For future reference, VMware releases always seem to come in bunches. Update 6 for vCenter 2.5 has been released and can be downloaded here.
The update mostly includes guest operating system custimization enhancements.
Guest Operating Systems Customization Improvements
Customization support for the following guest operating systems has been added in this release:
For more complete information about supported guests included in this release, see the VMware Compatibility Guide.
Windows 7 Enterprise (32-bit and 64-bit)
Windows 7 Ultimate (32-bit and 64-bit)
Windows 7 Professional (32-bit and 64-bit)
Windows 7 Home Premium (32-bit and 64-bit)
Windows Server 2008 R2 Standard Edition (64-bit)
Windows Server 2008 R2 Enterprise Edition (64-bit)
Windows Server 2008 R2 Datacenter Edition (64-bit)
Windows Server 2008 R2 Web Server (64-bit)
Support for Firefox 3.x Browsers with VirtualCenter Web Access
This release adds support for Firefox 3.x browsers with VirtualCenter Web Access. Firefox 3.x is not a supported browser for ESX Server 3.5 Update 5 Web Access with this release.