Whiptail is one of the high level herbs from the new expansion that continues to sell well into the second week of the expansion.
Whiptail can only be found in Uldum and only along the shoreline of the river and canal system through the middle of the zone. All else equal, farming Whiptail is probably inferior to farming Twilight Jasmine unless there is a significant price disparity between the two. Firstly, the Whiptail route is more easily monopolized by farmers because it is very distinct and straight-lined. Secondly, Crocolisks guard many of the nodes, meaning you'll need to be of appropriate level and ability in order to kill them. The red pathway in the diagram shows the optimal flight path for farming Whiptail. Unfortunately, you'll notice that it is rather short, which creates another problem: it's possible to out-fly the respawns, and nobody who is spending time to farm gold in World of Warcraft wants to sit idle waiting for a node to repopulate.
The other Herb that can be found in Uldum is Cinderbloom. It is dispersed evenly throughout much of the rest of the zone. If you combine Herbalism with Mining, Uldum becomes a potent WoW money-making spot. With only one or the other as a profession, you are at the mercy of other players and whether they've chosen to farm at the same time you have. Too many farmers and the pickings get very slim and frustrating, especially on a non-pvp server where there is no way to inhibit the opposing faction's flower-pickers.
Also, in case you decided to skip the Uldum experience (as it seems a lot of people are apt to do), go check it out! I think it is one of the prettiest zones in the game. Great Egyptian feel to it along with a nice flow of terrain and spectacular buildings.
Mount Hyjal Mining Route
Vashj'ir Mining Route
Deepholm Mining Route
Uldum Mining Route
Twilight Highlands 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
Tol Barad Azshara's Veil and Whiptail Herbalism Route