Hardcore PvP players pursued Enchanting for the ring enchants, for example, while hardcore raiders leveled their Leatherworking for the Drums of Battle. In Wrath of the Lich King, the different professions get even more exclusive goodies designed to keep professions more or less in tune with their intended classes. Eliah reported about the passive buffs for gatherers, and they seem to be in thematically tuned to some classes. Take Master of Anatomy, for example, which seems to be a benefit given to Skinners. Traditionally, Rogues, Hunters, and Shamans were the classes who pursued Leatherworking and its complementary profession, Skinning. The passive benefit to critical strikes are certainly welcome to those classes, so players who chose to stick to their Skinning will actually receive a pleasant boost in Wrath.
Then there are the new BoP wands for Enchanting, which Eliah also discussed, reaffirming Enchanting as the profession of choice for cloth-wearing classes. While the wands might not be better than some raid loot, the change rewards clothies who didn't drop Enchanting for Leatherworking. It benefits the casual players the most, allowing them to create arguably good items in preparation for raids. Blizzard continues to encourage choosing professions that are natural extensions of your class (and not like, say, a Priest taking up Blacksmithing).
I'm looking forward to what other BoP or profession-exclusive items or spells there are. It certainly adds some flavor to the game, and gives further incentive to players to actually level their professions. Providing benefits to gathering skills is a commendable idea, as well. Those tanks who stuck to Mining (for their Blacksmithing, presumably) should be pretty happy with the 35 Stamina bonus from Toughness. If Alex is right, Engineers might even be scooting around in BoP hogs in Northrend. My Stormherald served me well for such a long time that I'm pretty stoked to find out to its equivalent in Wrath. You can learn more about Wrath's BoP goodness over at MMO Champion's extensive professions galleries.