I guess this discussion has continued in a different thread.

I'm 75% sure revitalize does stack. In other words, if you have multiple HoTs on you from multiple druids, then you will have many chances to proc the extra mana/rage/energy/runic power.

This could be very interesting. For one it looks like my 5 resto druids can probably spam wild growth all day long and almost never run out of mana (due to so many revitalize procs happening). Also, it could be interesting to see if 3 resto druids and 2 rogues or 2 warriors is in any way a viable arena team. With a massive amount of healing to keep everyone up, and boosted energy/rage generation from revitalize, it may be enough to burst people down one at a time.