Is it possible to upload files to a website from Safari on iPhone?

I'm trying to upload a photo from my iPhone 4 to a website. However, the browse button to display the select file dialog is disabled. Normally this works fine on my Windows PC. Should I be able to select image files to upload from Safari on iPhone?

Specifically the browse button is disabled because there isn't a file browser (like Windows Explorer/Finder) on the iPhone. Most people don't notice that, because the iOS is designed around avoiding the need for a user interface to the iPhone's file system.

For simplicity's sake file management is turned into a programing problem instead of a user problem. For security's sake applications can't directly access the documents of other applications.

As Jawa mention, a lot of sites have iPhone applications to allow uploads.

As of iOS 6, Mobile Safari now supports file (image) uploads, from the Camera Roll, albums, and photostreams. Note that iOS 6 is only available for the iPhone 3GS and newer.