its not really out there yet. i've done the email idea above, using gmail to handle the the mails.
one of the hang ups is that iOS does not allow safari to access/upload images at all. other thing i was toying with (but haven't seriously deployed) was using
Picup to get around that. basically the iOS user would have to install this (free) app, then it takes over the upload form elements on detection, sends the image to a free image host, and then posts back to you so you can take over from there.