<<Michael:
I want the grouping mechanism to enable a hierarchical structure so you could have parent and child groups.>>

This will help Moi to be more quick and easy to use...i mean:on a hand we got the best UI,quick and powerful tools;on the other we have a basic grouping mechanism that often deboost workflow.
(you see,Michael, users that post models more complicated are growing,lot of sub-objects,details etc...)