With the Connect-VIServer cmdlet you can connect to multiple vSphere servers.
Only condition is that you can use the same credentials, or that SSO is implemented.
When you switch to 'multiple' mode with the Set-PowerCLIConfiguration cmdlet, you can launch cmdlets against all these servers at once.
You can now do a 'Get-VM' which will return all the VMs on all the connected vSphere servers.