How about the other direction. Say you took this picture on a camera and want to save it as wallpaper to your cell phone.

Took me a while to Google this and I ended up calling AT&T to find the information. Evidentally this is some type of secret. Your cell phone has an email address:
yourcellphonenumber@mms.att.net -> at&t (formerly cingular)
You may need to call your provider to get the address for your cell phone.
