Okay well this is just a little exploit to use in Wintergrasp when defending the orb (in those long matches where Alliance undoubtedly have 10+ tenacity and destroy all your walls quickly). The trick simply is to blink from the stairs leading up to the orb so that you end up... inside! From here you can easily see any alliance trying to cap the orb and also (take my word for it) Arcane Explosion can hit everyone attempting to cap from the middle of the orb.
You still take dmg from aoe attacks on the orb as it is not considered a solid object.
Enjoy, here are screenies(pre-blink and post-blink)
http://img530.imageshack.us/img530/5511/blinkcq8.jpg
http://img210.imageshack.us/img210/6032/orbzu8.jpg
Sorry for the big resolution.