The release of vSphere 5.1 introduces support for OS X 10.8 and 10.8.1 on ESXi 5.1, with the following support considerations:
- Installation instruction can be found here http://partnerweb.vmware.com/GOSIG/MacOSX_10_8.html
- vSphere Client does not have a specific selection for “OS X 10.8”, but “Mac OS X 10.7” can be used instead.
For more information about software support, please check the VMware Compatibility Guide