Seems that Valve are mighty pissed about the suggestion that adverts will soon be appearing in Counter-Strike: Source, they certainly didn't authorise it by the looks of things. Read more on GamePro

Doug Lombardi;

At no time did Valve grant permission nor discuss these advertisements with Engage. As such, this is now a legal matter. Advertising or any other commercial use of our games requires our written permission.

Ouch, Thanks Slashdot. I'm personally of the option that CS: S would be more entertaining with a few adverts, it can't be worse anyway, hehe.