World Of Warcraft: Gruul/Magtheridon adjustment ETA?

Tigole has some info on the encounter and when it will be adjusted to the desired difficulty rating we all want:

Right now, the changes are planned for 2.1.0. We'd like to see the changes on the PTR before pushing them live.

2.1.0 is the next content update. There might be a 2..0.11 but that would be an emergency bug fix patch.