Valve’s content delivery service, has evidently been hacked. According to a posting made on an anti-STEAM website, MaddoxX has successfully bypassed Valve’s security system and accessed a significant chunk of data, including the following:-

>Screenshots of internal Valve web pages
>A portion of Valve’s Cafe directory
>Error logs
>Credit card information of customers
>Financial information on Valve

The info sqeezed out by MaddoxX was later posted on an anti-Steam website, where the culprit also threatened to release a spreadsheet of the credit card information. So far, Valve hasn’t made any official statements regarding these thefts.
It could be dangerous as madoxx already knows how much they have with them at present.