The Basic idea for this exploit is from the following thread, but you have to bind your hearthstone in Dalaran or near Dalaran: MMOwned
step 1: join an arena (skirmish works best)
step 2: if it is not ring of valor, keep doing skirmishes til you get a ring of valor
step 3: once you are in ring of valor simply log out and back in (wait 1-2 min before logging back in)
step 4: You are now in the bugged state (until you relog)
When you are in the bugged state you can queue in various Battlegrounds causing the following effects:
Alterac Valley (Horde only): You start at the Alliance Starting Point, causing some confusion. Once you are killed by the allies or the guards you will respawn at the Iceblood graveyard and are able to tap bunkers or graveyards before the game starts.
Warsong Gulch (Horde only): Once again, you will spawn at the Alliance Starting Point. If you have stealth you can hide here and tap the flag, once the game starts (sorry no screen for that)
Arathi basin (any faction): You start directly at the mine and can tap it and other bases before the game starts. (You have to bind your HS at the Argent Crusade Base in Zul Drak for this)
Eye of the Storm (any faction): You start near the Alliance Starting Point and can once again take bases before the game starts.
Strand of the Ancients (Alliance only): You start at the southern graveyard. If you can hide there until nobody guards the graveyard, you might be able to tap it before the gates are down (needs testing, since I have no Alliance char)
Have fun with those Exploits
Ps: If you bind your HS at the Argent Crusade Base in Zul Drak and then use a Mage Portal to Kalimdor you will land in Mt. Hyjal, but will be summoned out immediately because of "No Mans Land".