To my knowledge, accurately building and calibrating a stereoscopic camera is a significant pain. Saying you could just wave your phone around and extrapolate a 3D scene is easily 10+ years out, because people make terrible tripods, and the requirements for planarity, etc. to do stereoscopic well are pretty strict. That said, there are 3D phones with parallax screens and stereo cameras; they're big and bulky and not that great.
The cool thing I saw about Lytro isn't their flash based player. Its the idea of giving you another degree of freedom after a picture is taken. Like colour correction, you can do focus correction, DOF correction, etc. I would still export one flat image as a result, but gaining that flexibility without carrying around a monopod to take 10 bracketed images is awesome to me.
See my response above. Did not mean to suggest we should all start waving our cameras. Something could "wave" internally, or this waving isn't even needed of Canon came out with a microlens-adaptor.
By the way, there are several apps already which build 3D scenes from two separate pictures. Some can even generate 3D models. HDR used to require manual exposure bracketing in phones too. Now technology has caught up.
Correct me if I'm wrong, but the Lytro stereoscopic field looks fixed at a relatively short distance. At the moment it seems to be a very subtle parallax effect, one that might be mimicked by an ever so slight movement of a camera sensor.
I'd love to have that freedom... combined with everything else that I've come to expect from a DSLR. Lytro's cameras are nice novelty gadgets but it's not clear to me if they're trying to move in the direction of working with a sensor/DSLR maker to enable this. I think that's what they should focus on...
I gave this some thought below, but unfortunately fitting a new, more expensive sensor is probably not going to happen soon. The current 1.8 megapixel is a cheap commodity sensor, and it's still probably costing them buckets to have them fabbed with their custom microlenses. Something like a Kodak 8MP sensor would probably be 20x as expensive, and talking them into making you a custom SKU would be much harder.
Edit: after a bit of digging, it looks like they make the micro lens array themselves and buy the sensors without one. This obviously makes acquisition easier, but as the pixel pitch decreases ( by an order of magnitude, to compete with a modern SLR ) the complexities of building and attaching that array increase significantly.