don't know of a widget, but it's not too tough to write something like this... access the camera, save image to a bitmapdata object, use as3corelib to encode it to jpeg (http://github.com/mikechambers/as3corelib)and post it to your server using PHP or other middleware script.
This tutorial gets you pretty close to where you want to be:
http:// www.adobe.com/devnet/air/ajax/quickstart/articles/jpeg_file_upload.html
If you don't want to write your own, you could always buy a component:
http://www.buystockflash.com/Take-My-Picture-v1.0-/-WebCam/flash-animation-251.html