Hi Sean,
vSphere 4 is supported, but vSphere 5 is experimental. Several folks have got it working without problems, but it's not officially supported yet.
Pretty much anything you can do with the vSphere PowerCLI 5 or VSC APIs, you can automate through WFA. But, as far as I know, the vSphere PowerCLI doesn't have any View-specific Cmdlets.
Hope this helps,
Dave