I don't really know that too, and I'm not sure how does that really differ from IRmapping or Keymasters implementation of Irradiance caching that was in corona before... Or maybe some HDcache mutants :D lol one for primary GI maybe to do some more detailed high frequency details/lighting other to do a base rough computation if that's possible..
Now you guys might not like this :D but something like mental ray is doing when used GI+FG or IP+importance driven FG yields really nice convincing lighting extremely fast. The only problem that I think could appear when something like this was present in corona, would be how to minimize the amount of controls for this to be able to get good results..
