At any rate, it looks like the Pet Store is here to stay. Besides, Blizzard has already been hawking in-game services for real money, so it's not as if these vanity pets are any different. I personally don't find anything wrong with these pets, and seeing the number of diminutive liches and kung fu pandas showing up all over Azeroth, it really seems like a lot of other people don't, either.
Blizzard states that these items, similar to the TCG loot cards, are "purely cosmetic and just for fun." They say that they'd be loathe to introduce things that are "detrimental to the game and (detracts) from the gameplay experience for players who choose not to use the service." So that probably means no epic weapons or anything of the sort.
How far does that go, though? Are heirloom items considered detrimental to the game? How about buying levels? Premades? I personally wouldn't mind paying a fair price to skip the painful leveling process (an attitude that might admittedly change during the Cataclysm). What's do you think is next for Blizzard? Armor dyes, perhaps? Vanity outfits such as the complete Brewfest set or gag items such as those found on the TCG? Titles? Now that the microtransactions gate has been opened, how far do you think Blizzard will go?