There seems to be a pretty widespread hack going around WordPress websites. If you upgrade to the latest version, you should be safe:
I helped clean up 2 hacked WP sites this last weekend. The hack wasn't too bad. It involved the hacker inserting an iframe at the top of the page. The problem was that those sites were reported as malware sites and Firefox was displaying a message to people that the sites were accused of spreading malware instead of those websites getting traffic. The fact is, that site itself wasn't spreading the malware since another website was being framed.
Please make sure you upgrade WordPress immediately. If you need help cleaning up a hack, let us know and we can help with our website maintenance service.