Wow, that's a cool idea. Personally, I think the most important part is to implement the function of clicking once, and the camera takes a series pictures suitable for HDR. The actual imageprocessing could be done on the desktop to start with. I think it is fair to demand that the camera is held steady while the camera takes the image series. Otherwise the problem is unfeasible I think. However, for people interested in HDR I think it would be possible to construct a some sort of jigg for attaching the N900 to a normal tripod.