They haven't made the full announcement yet but they've revealed info on their next handheld.  This isn't a regurgitated DS, its the next model.

So far we know that its:
-backwards compatible with DS
-has some sort of 3d screen which doesn't require glasses
-Most importantly it has a relatively high res screen of 1280 x 768 (5 in screen)

I expect this thing will be vastly more capable in terms of processing power compared to a DS or even compared to an iPhone for that matter.  It will be interesting to see how Sony and MS respond, but for the first time in years Nintendo is giving us something to be optimistic about.