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.

The high res screen thing I like. The 3D thing I'm completely indifferent to. Is there really need for a 3D-capable handheld?

(Just as much need as there was for a touch-sensitive folding Gameboy, I suppose, but still...)

The 3D screen sounds pretty cool to me.  I would like to see it in person.  I will never get a handheld system though.

Yeah I'm not too interested in the 3d capability either although I'll reserve judgement until I see it.  I'm curious as to how its supposed to work without glasses.  I'm thinking the the effect is reversed, rather than pop out at you it has depth away from you.  Sort of like an infinity mirror without things being repeated. 

Found this:
http://www.youtube.com/watch?v=h5QSclrIdlE

It's for the DSi, probably the same thing.  I think it uses the built in camera to detect the users eyes/face and the software makes changes to the displayed perspective accordingly.

But just the fact that it will be able to do 3d graphics properly with a decent res is a big improvement...

Agent Ghost

  It will be interesting to see how Sony and MS respond.

Does not matter how they will respond, Yet again, they'll be poorly executed and lost most of the potential market (to this). Nintendo are always a step ahead of the competition.

Nintendo's biggest and most credible threat in the handheld space is Apple.