Browsing through talk pages I noticed the following: A new user had asked another user a question and started it with @username. He probably expected the other user to be notified, but as it does not work this way in mediawiki, never got an answer.

So, it would be easy to do a javascript, that scans through input boxes and if a "@" at the start of a line or preceded by a space is found, then if the following word matches an user name or a sig of an user that is either mentioned on the page or can be verified by an api call to be a local user, then the script opens a box with a text that tells an ip-user to login and then use ping, or asks a logged in user, if this should be transformed to a wiki link to that user.

But this does only make sense, if it is not an user script or gadget, but only if it is integrated in the system javascript of all wm-sites.

Additionaly there could be gadgets to allow experienced users to opt out or alternatively to skip the box questioning, if the transformation should be made.

Local wikis could set a configuration variable, so that the script inserts a local ping template instead.