The good news is Microsoft already has a patch out to fix this vulnerability (released on April 3rd), so go download it (auto-update will get it) and you should be safe. One interesting factoid in the BBC article on this flaw is that the value of a WoW account is now greater than the value of a credit card, at $10 and $6 respectively. What's so useful about the average WoW account that it's worth $10 on the open market?
Update: You can find the download link for Microsoft's patch in our previous article on this vulnerability. Please download the patch if you have not already.