Unfortunately, the idea doesn't quite fly with me. In an online situation like, say Facebook, you're more or less playing yourself-- odds are you've posted your own picture, your own opinions, and your own favorite music. But in World of Warcraft, you're playing a character. And even if that character isn't completely different from your real-life persona (most people actually are themselves in the game, unlike hardcore roleplayers), it's still different enough, in my opinion, to be a significant barrier to actually judging someone as a relationship partner.
But that's just me-- lots of people have found significant others in online games, and even more have met lots of people in MMOs, and then actually become better friends or partners after meeting them in real life. But while an online space like Myspace or Facebook might be very conducive to getting a real sense of new people, an online game set in a fictional universe like WoW is still too separate from the real world to allow for a real love connection on its own.