This is possible, but you'll need to dig into the actual template in the catalog. for examples:
PowerCLI C:\> $temp = Get-Catalog "Brian Graf" | Get-CIVAppTemplate "vRB std w/PowerCLI 5.8 -BG"
The following will display all the VM's within the template. there are several ways you can get metadata off those vms
$temp.ExtensionData.Children.vm
You can get the metadata off of a specific VM by specifying it's order
$temp.ExtensionData.Children.vm[2].Getmetadata()
Hope this helps.
Senior Product Manager - Distributed Resource Management | @vBrianGraf