Is there any module for picking photos for image field on mobile platforms like iphone I think this is probably impossible but I wondered if there was any way to provide image upload or equivalent for mobile platforms for drupal.
No, you'll need to write an iphone application to do the photo upload (using a web service).

There is an older post with more info. 

With Android phones the regular photo upload works, at least that's what I heard from a couple of users.