They obviously use the same style as all of the other in-game maps, with labels of each area and concept art of the dungeon itself behind each layout. But here's something we didn't expect: each map has a skull placed where the bosses are, so with just a glance at the map you can see where the big bad guys are found. Right now, obviously, we know where they all are, but that will be interesting when maps of future instances become available.
And right now, on the world map, areas get drawn in as you discover them, but we'd guess that these maps will be opened up as soon as you enter the instance (you don't discover parts of an instance, you discover the whole thing). It'll be interesting to see, next time we explore some new instanced content, just how these maps can affect gameplay.
Patch 3.1 brings us Ulduar, dual specs, significant changes to all the classes, and more! We've got you covered from top to bottom with our Guide to Patch 3.1.