For supported Guest/Host OSes have a look at the Guest/Host OS tab on the VMware Compatibility Guide Web site.
Also read all Release Notes for the Product version and previous point versions for the Product version you're using.
As far as Ubuntu 12.04 working with the built in VNC I'd be surprised if it didn't work. That is of course assuming your using a version of the VMware Product that supports the Guest OS you're using!