I contacted Steam Support and they sent me this:
Message by Support Tech John on Sun, 23rd Jun 2013 8:51 am
Thank you for taking the time to report this issue.
We are aware of the problem with the invalid CD keys, and are investigating the issue further.
For news regarding the latest updates and patches, please check the SteamPowered News page:
Note: This message was sent in response to your ticket based on categorization. If this message does not apply to you, please update your ticket with more information.
I guess it means they know what going on at least