I just went to Methods wepside, and they have posted that they havent downed any bosses at all in a dungeon named: Sunwell.
I dont know what sunwell is? is it harder then BT? is it in the game? or will it come in an upcoming patch ?

they may be referring to Tempest Keep the Eye because Kael'thas is in there

Its a new instance north of silvermoon thats coming out in patch 2.4 and it is harder than BT but there is no T7. and the area is kind of like situlis (dont know how to spell it)the more quests you do the bigger the area is and i heard that the last 3 bosses you need to unlock by rep. And its also a 5-man instance.

i think the reason its harder is cause of the 5 man part

with it being a 5 man and all, the difficulty would most likley be trying to 5 man ZA with longer boss timers, really i dont give a crap as i doubt ill ever get here or even attuned =P

actually the sunwell has a raid and a 5 man instance too kinda like how hellfire citadel has 3 instances and a raid, its gonna have new daily quest there and in heroic mode the 5 man instance has kael as last boss and drops loots as good as kara and the 25 man raid is suppose to be above t6 but no t7

Ummm Sunwell is a 25 man raid, Magisters Terrace is a 5 man Instance.