As a result of Patch 2.3 the requirements for Heroics was lowered from select faction Revered to Honoured. You no longer have to prove you got the chops been tested and Revered with blue gear to prove your somewhat ready to perform at Heroic level. Anyone at Honoured for the select instance faction at lvl 70 can now find a group.... or try to and venture into a Heroic level Dungeon. Willing to risk life and limb being unprepared and most likely put 4 other unsuspecting people at death's gate.
If your a new Paladin tank or if your another tanking class do your self and other people a huge favor and be prepared! As Illidan says.. you are not prepared! For Paladins you need some damn good blue gear. You need 485 Defense minimum for Heroics and at least 10K HP minimum to make a decent shot at doing Heroics. I would say 11K HP would be a lot better and you would be doing the Healer and the other DPS a huge favor in you having survivability in front of melee mobs that hit from out of this world HARD. They hit harder than mobs in Karazhan. Just because you tanked a few instances new at 70 don't mean you should venture into Heroics with crappy gear and crappy greens and think your going to survive. You won't in one piece! Your going to be running up lots of people's repair bill being unprepared. That's goes to DPS as well as Healers who lack healing power also. I love PuG's but I sure won't be in yours in Heroic mode!