Well, it looks like some of the bosses may have been a bit too easy afterall. Daelo posted on the Raids & Dungeons Forum that there are some changes being made to the difficulty of certain bosses in Black Temple and Hyjal.
Based upon further feedback from guilds in Black Temple and Hyjal, we've decided to make some difficulty adjustments to many of the later bosses. As a general rule, the changes increase the damage dealt by the encounter to the raid. Note that due to the timing and nature of the changes made, some of the tooltips for the retuned abilities will be incorrect.
The encounters changed include:
The Illidari Council
Our intent is not to make the encounters impossible. Even with the increased difficulty, I do expect some of them to be quickly beaten again after guilds experience the changes and adapt.
As a side note, the 2.1.1 patch did include the change to the Archimonde encounter that increases his leash distance and made the Well of Eternity a bad place for casters to be near.