For CUPS, the contact images are stored on a different web server than CUPS so there's no standards based approach or logical path for end-users to be able to post or write images to this 3rd party web server to change or overwrite their image. The good news is that this allows the IT Staff more control over what images show up for the end-users, which HR and Legal departments love.
However, if this is a concern for your environment, you could create a customized page and integrate it into the Jabber client (by using the Jabber SDK) to allow your end-users to be able to upload any image they want to your 3rd party web server which Jabber then syncs with through the settings in the jabber-config.xml file.
