Hey,
first of all I know that this isn't really an exploit, it's more like a clever usage of the game mechanics. Many warlocks know about the demonic circle trick in WSG. Use your demonic circle on the roof, jump down and if you get in trouble -> use your port.
While doing rated BG's with my premade, I figured out another neat trick. As a flag carrier I have to survive as long as possible so this trick will allow you to kite several enemies in the Silverwing Hold / Warsong Lumber Mill for a long while. (it works for horde and alliance)
1.) use your demonic circle on the roof, near to the wall:
Alliance:
[SPOILER][/SPOILER]
Horde:
[SPOILER][/SPOILER]
2.) jump down and run outside to the graveyard.
3.) if you're close enough to the building you'll be able to use your warlock port:
Alliance:
[SPOILER][/SPOILER]
Horde:
[SPOILER][/SPOILER]
4.) you get in trouble? then use your warlock port:
Alliance:
[SPOILER][/SPOILER]
Horde:
[SPOILER][/SPOILER]
5.) your enemies have to run all the way from the graveyard to the roof (this takes more than 40sec so your warlock port should be ready again)
6.) repeat step 2.) - 5.)
Have fun.