You would be surprised at how much power a small solar panel can generate (if its a good panel) I have a solar panel outside my house and is about 1 inch around bigger than my iphone and it runs my 3800gph pump for my pond.. and since the NEW iphones run on 5volts, it doesnt require all that much juice, the older iphones probably need to be left out just a LITTLE bit longer, but not much of a difference.
on the other hand, instead of crank, they have the friction generators. You just shake up the case, it causes friction, which is then turned into power and you can use it ANYTIME, ANYWHERE.. now THAT is something i might actually buy!!
I mean think about it, you are stuck on a train and you were playing poker for the hour long ride after surfing the web for the hour before that.. then you need to go into a 3 hour meeting. By the time you get out, your phone could be DEAD.. so instead of NOT playing the games and trying to conserve battery, you just use as MUCH juice as you want and then just shake up your iphone case and plug in the phone..
No sun required (your not always outside, right?) AND it is rather small technology.
I think i'm gonna talk to my engineers about making this

I think i'm on to something.