You can't actually use that as a client though, if you want to link someone to an add-on you can type this in the chat:
http://rtb-<fileid>
Which will show a very unfriendly "rtb-fileid" link. It might be possible to make a special thing you can type that will display correctly for other RTB users, like [rtb:Sawn-off Shotgun] or something. It'd show up as "[rtb:Sawn-off Shotgun]" for all non-rtb users though, but thats not a problem.
How are the chances for a better build gallery looking?
I've been looking into this a bit, although it is quite far back on the list of things to do. One thing i'd expect to include with that would be the ability to upload saves and screenshots from in-game to the build gallery for other people to download in-game, however due to engine limitations file uploading isn't actually possible at this stage, but if Badspot includes this little engine mod I whipped up to allow it into v11/v12, we should be in business.
May I suggest a simple gui that searches for a random person and the server that there in. Like you open the gui, type in the blid/name and find the person and the server that their in.
That will be something that will be available in RTB Connect for sure, provided the person you're searching for has allowed non-buddies to search for what server they're on in their privacy settings.