The WordPress Support forums have been updated to include Twitter/GitHub style auto-completion for usernames. As users begin typing @username in the forum’s TinyMCE editor, it will begin to suggest usernames, narrowed further by characters typed. Hitting tab or enter will complete the username and link it to the user’s profiles.wordpress.org page. This will trigger a notification for the user.

8991b6f02fdbd269922836036c4ac269 WordPress Support Forums Add @mentions with Auto-complete design tips

A similar feature was implemented on WordPress trac three years ago. This initial version of @mention auto-complete for the support forums works in a similar way in that it completes a partial search query from a known set of usernames. In this case it only includes thread participants. In order to make the auto-complete scale for WordPress.org’s 10+ million registered users, it does not perform site-wide username lookups or include moderators, plugin reps, or theme reps who have not yet commented on the thread.

The @mentions have been implemented across all WordPress.org forums. Any issues with the feature can be reported on trac by re-opening the original ticket or creating a new one. Daniel Iser commented on the ticket that he is working on getting this feature working for bbPress during the first half of this year.