As part of my effort to explore and do as many things as possible, I decided to join my first battleground (currently level 18, so I won't be a drag for team mates) by doing it in the original 1.5 fashion: Going all the way to the instance portal in the area where the faction has its base.
It took me a bit of time to head all the way to the Silverwing Grove since I hadn't been yet to Kalimdor, but after a while I get there, run into the red instance portal and.... nothing happens. So I dig up the patch history of battlegrounds, and see that 10-19 bracket for WSG was only available from patch 1.8, but after asking around, it seems the bracket is indeed working when people use a battlemaster to queue.
A few minutes later a night elf hunter comes along with the same plan, and she has the same issue even though she is level 27. Running into the portal is not starting the queue.
Here is a screenshot for evidence:
http://imgur.com/WMB7GF9