I found four in the Towlong Steppes alone, and I wasn't really looking all that hard. In fact, I stumbled across one on a remote island to the north of the Steppes while flying around after dinging 90 and ended up doing that one first. The quests range from simple "collect X of Y" quests to slightly more complicated exercises, and they tend to fill in gaps in the lore as well, if you're interested in that.
Anne Stickney and I did one of the quests together, and there were some odd issues with looting quest items that we worked out. In general, the quest didn't take very long once we got into the swing of it, and it was a fairly painless way to farm up five valor points overall. While dungeons still offer points as well, it's a nice supplement.
It's open warfare between Alliance and Horde in Mists of Pandaria, World of Warcraft's next expansion. Jump into five new levels with new talents and class mechanics, try the new monk class, and create a pandaren character to ally with either Horde or Alliance. Look for expansion basics in our Mists FAQ, or dig into our spring press event coverage for more details!