The Club released a statement in an email and over their social networks (though I can't seem to find a direct link):
Just to let everyone know, we upgraded our online security systems as we understand that credit card theft is a growing problem in the U.S. Online security is a serious business and Fun Publications takes it seriously. We have implemented an ongoing review process of these security systems so that as internet thieves become more sophisticated, so will our defense systems. If you have any concerns, please let us know. When you order from anyone on any kind of device, make sure that https starts the url. This means it is under a secure socket layer and is encrypted during transmission. Additionally all information in our database is encrypted under a 256K algorithm.
We have been following the talk regarding the fraud problems but we haven't confirmed how many, if any, were on our end. This upgrade was a precautionary measure. Fraud can come from many sources and it is difficult to determine with 100% certainty what happened in those cases. We are dedicated to solving any problems and will do whatever is necessary to make shopping with the Club a secure experience.
If you have any concerns, please do not hesitate to contact us 1-800-772-6673
We wanted to make sure people here were aware that there MAY be an issue with credit cards used at the Club's online store or for Botcon registration, and that it would be a good idea to keep an eye on your credit card statements for suspicious activity. If you find some, and you've bought anything from the Club in the past year or so, please report the issue to the Club to help them figure out if it's related to their services. They won't be able to help anyone if people don't report the issues to them directly.