Is it possible to write a HTML5 web application designed for the iOS devices (iPad, iPhone, iPod Touch) which can allow the user to upload an image from the filesystem?
Imagine uploading a new photo to your twitter avatar via a web app.
I hate this word, but, it's impossible (up now). Here is the reasons:
1) mobile safari doesn't support upload anything.
2) mobile safari can't access ios components (actually it can, but, only through phonegap)
UPDATE: iOs 6 Safari is going to support upload videos and images from the Photo Library.