Reader Dave sent word of another bug in the game after the latest patch (thanks!) that might cost players some money. A player was trying to sell his Hyacinth pet on the Auction House (there's a small craze on vanity pets right now, thanks to the achievements) when he ran into a problem -- an error told him that you couldn't AH "an item with used charges." Except that he hadn't used the pet yet -- it wasn't in his pets screen. But Blues have confirmed that with pets purchased or obtained but not used before the patch, this can happen -- the pet will be unsellable.
Darkmoon Faire cards are apparently having the same issue, but as you might expect, it's unlikely that Blizzard will take steps to fix this, both because all we're talking about here is AH selling (not a critical game mechanic), and because this problem doesn't seem to be affecting new pets and cards, only cards that were purchased and owned before the patch. But maybe they will hotfix it, we'll just have to wait and see.
Anyone that horded pets to sell on the AH could be in trouble, though -- if you've got a significant amount of gold stored up in pets you were intending to sell, you might be out ot luck.