I had a question about how to query VC and ESX for their version numbers, so I wanted to post the answer here.

If you're connected directly to VC, use this to get the VC version number:

# Version info about the system to which you are connected (VC or ESX).
$si = get-view serviceinstance
$si.content.about | select Version, Build, FullName

If you want the versions of the servers managed by VC instead, use this:

# When connected to VC, get info about the hosts managed by VC.
function Get-VMHostVersions {
 get-vmhost | % { $server = $_ | get-view; $server.Config.Product | select { $server.Name }, Version, Build, FullName }
}
Get-VMHostVersions | fl *