Any update about D5100 successor?

I'm planning to move from m4/3 to DSLR world and have been looking for at Nikon D5100 as it seems to fill majority of my requirements but I've been holding on the purchase because I've been reading rumors about a successor to D5100 coming soon.

Does anyone have any insight when we might expect the release?  Also, based on past Nikon refreshes, what changes should we expect from D5100?