Just rediscovering this album from last year. I didn't really give it a shot at the time. Happy to be wrong about it.
My Resto Druid hit 80 a little while ago, and suddenly I couldn't queue for ANY dungeons, not regulars, not heroics, not early Cata, NOTHING. NO THING. I had leveled up through the dungeons picking up decent dungeon gear, but I don't get even a chance at Heroics now? I am confused.
You're prohibited from queueing for certain dungeons and dungeon types by your item level. A fresh 80 who got there by questing probably won't have the requisite item level to do Cataclysm dungeons and not enough to do Wrath heroics, either. It's better this way, believe me. Quest for a little while. Get some gear.