New NXT and PF parts?
TechnicBricks have found some very interesting pictures of (possibly) upcoming NXT and Power Function parts. Read their full post for more pictures. Given the look of this windmill, it seems to be an expansion pack from LEGO education, but perhaps the parts are useful for your own robots as well.
I could also imagine it is a slightly more efficient dynamo/ generator.
Common PF motors can generate power also if you turn their motor shaft, but that requires a fair bit of force. Maybe this one has less internal friction (less rpm changing gears) to compensate for this problem.
This little generator could recharge the PF battery pack, or something like that. But, I'm just speculating :-)
A new rechargeable battery pack for the NXT: DC, not AC like the current one, and with significantly increased capacity (150% of the current version).
A new PF motor that explicitly states it can be used as a generator.
A new sensor adaptor to interface with Logit sensors for datalogging etc.
At least one image that seems to show the new solar cell used in some way with the NXT... and also shows an NXT-style port on the energy meter, so it seems to be readable by the NXT. Also, the new solar cell is higher voltage but lower current than the old one.
The small energy storage Ni-MH battery (150 mAh?) is awfully small; I suspect as an effectual replacement for the capacitor (still available apparently, but lower voltage when charged like the old solar cell).
I'm presently working on a solar powered cuckoo clock, but as a previous post points out the inbuilt battery is very small in capacity.