Isnt it quite clear that Apple will release the updated MBPs with Mountain Lion? And thats most likely sometime in late June and early July, everything points towards a mid year release, the supply chains, the timing of the IB chips, the sheer lack of any solid evidence floating around right now.
To top it off Apple isnt going to make you buy a brand new model only having to update the OS a couple of months later. I'm sorry to those guys waiting for an April/May release but its simply not going to happen.