Basically as part of the recent patch, it will kick you out of Wintergrasp in 3-5 seconds if a battle is going on and you're not part of the raid.
I was afking in Wintergrasp while the battle was going on and the auto afk flag came on. If you go afk in Wintergrasp you're automatically kicked from WG. I tried to requeue for WG and was put into queue.
So I flew to Wintergrasp from the southern edge of Icecrown, directly north of the Wintergrasp fortress. I checked on the amount of time remaining in the battle before it ported me out in 3-5 seconds.
Here's the exploit. Wait until the battle is about to be over with ~ 5 seconds remaining by flying in and checking on when the battle is going to be over. Fly in during the time when the battle is over within the 3-5 second window before you get ported out, you will be credited with the honor/marks you would earn as if you were part of the battle!
Of course in order to earn more than the default 1 mark for win/loss you would have to make some kind of rank "corporal, first lieutenant" You might be able to fly in and try to get close enough to some honor kills if the battle is going on right at the doors before the orb.
TL DR version
Be in Wintergrasp when the battle ends during the 3-5 second window before it ports you out. Even though you're not in the raid you will still earn honor and 1 mark for win/loss. If you happen to have "corporal, first lieutenant" ranking you will earn more marks.