Read some confirming/info from Zarhym - and i'm quite upset that i will not be getting a skeleton bear mount from Zul' Gurman. The new raid instance will be Ruby Sanctum: a single boss encounter that will have sub bosses that drop emblems of frost (ala Sarth). However unlike Sarth (unfortunately) there will be no gradually esclating hard mode mechanic (1-2-3 drake). My guess hard mode will give the boss simply an HP/Damage boost and one or two new abilities and/or adds.
Most of the new blue posts on the subject can be found here.