Essentially, these guys hacked into thousands of websites and added a small amount of code that redirects users into an invisible attack from some China-based servers. Apparently if you've got your antivirus program of choice up-to-date you shouldn't worry. Although the article points out that some of these attacks are directed at ActiveX controls, so update that as well if you haven't recently.
We all know how terrible it would be to have our accounts hacked into and stolen. Many of us spend hundreds of hours in our favorite worlds, which many of us also pay for through our credit cards. Strangely enough, Lord of the Rings Online is mentioned as one of the games targeted by the hackers.