There is a tab when you select Tools->Connect from Ops Console that is called "Registered Servers". It actually will go into your AD and query for CN=SDKServiceSCP, which is a container that stores information on your Management Groups and RMS servers:
It normally works well, but there are a few gotcha's:
1. if you want to delete old management groups. You can find the RMS computer object in AD and from there find the corresponding SDKServiceSCP:
If you delete the SDKServiceSCP the server and corresponding management group will be gone from the registered servers view
2. If you have a clustered RMS you will notice that you have the SDKServiceSCP ONLY for the 1st node of the cluster. To have the correct cluster RMS name in the registered server, go into the SDKServiceSCP and modify these two attributes to the proper cluster instead of node name:
serviceBindingInformation and serviceDNSName
I was told unofficially that this should be fixed in next SP release for OpsMgr.
I thought I would post the above, as it seems this is nowhere documented.