Can an Operations Manager 2012 Agent report to an Operations Manager 2007(not R2) Management Group?
Yes it can.
Just install the Operations Manager 2012 Agent onto the server. Go to control panel and open the “Operations Manager Agent Properties”, add the 2007 Management Group. The server will show up in the “Agent Pending” group of your 2007 Management console. Go and Approve it.
In Operations Manager 2007 (not R2)
In Operations Manager 2012
So now your server is reporting to both Management Groups. Usefull to know if you’re planning a side by side installation of SCOM 2012 next to SCOM 2007.