With the release of World of Warcraft Cataclysm expansion, you cannot use the dungeon finder to queue for Cataclysm instances until you “discover” the entrances to them. Here’s a lisit of locations and coordinates to get you started:
ULDUM INSTANCES
Vortex Pinnnacle (levels 82-84) 77,84
Halls of Origination (level 85) 72,52
Lost city of Tol’vir (levels 82-84) 61.64

TWILIGHT HIGHLANDS
Grim Batol (level 85) 19,54

DEEPHOLM
Stonecore (levels 82-84) 47,52

VASHJ’IR
Throne of the Tides (levels 80-81) 71,29

BLACKROCK CAVERNS level 80-81, is located off east side of main ring in Blackrock Mountain, (between Searing Gorge and Burning Steppes)