Uldum possesses the best Elementium Ore mining route in the Cataclysm expansion.
About one in every fifteen nodes produces a Pyrite Ore node. The success of this route will entirely depend on how many other players are running on it. Node locations are plentiful and predictable, which means if you can get the timing down, you can be hitting nodes almost as they respawn, which can drive other farmers away if you are persistent. Unfortunately, this area is destined to likely be the new Scholazar Basin for gold-farmers, which may make it unserviceable for players just looking to augment their bank account. Uldum was fortunate not to be hit with the nerf of mining and herbalism nodes that Deepholm and Twilight Highlands suffered soon after the launch of Cataclysm, which means that mining and herbalism nodes are plentiful.
As you can see from the WoW map of Uldum, the optimal Elementium Ore mining route is represented by the blue solid line. If the zone is being heavily farmed, you can choose to swing south on the optional route (blue-dashed line), which holds about a third of the nodes per distance traveled as does the optimal route. The map also shows the route for the herb "Whiptail", which only grows in this zone and may rival Twilight Jasmine as one of the most sought after herbs of the Cataclysm expansion. If you can combine mining with herbalism, there is a fortune waiting to be made in Uldum. As it stands, if you can catch this zone at an off hour, it is probably the best zone for making money in WoW by mining, and perhaps runner-up for herbalism.
Mount Hyjal Mining Route
Vashj'ir Mining Route
Deepholm Mining Route
Uldum Mining Route
Twilight Highlands Mining Route
Tol Barad Mining Route
Mount Hyjal Herbalism Route
Vashj'ir Azshara's Veil and Stormvine Route
Deepholm Heartblossom Route
Uldum Whiptail Route
Twilight Highlands Twilight Jasmine Route