Am I the only one who is dreaming of an email client?  webmail doesn't do it for me.  A real client would be amazing.<p>Seriously though, let's consider.  I hear of tons of apps that are really clever on the iPhone store, and many of them do not use the camera, gfx, gps or accelerometer.  It's true the iPhone has more computing power, but both have 3G.<p>My mind's not in a state right now to do a real comparison, but in my opinion, quite a number of the clever and/or useful iPhone apps I've seen could be ported to the Kindle.
(this is not of course to say that's what should be done, or even that would be the limit- after all, Kindle has a much larger screen- just as an idea of the spread!)