Piracy and copyright infringement is a really hot button issue these days. So is plagiarism. It's interest, then, to see that a company called Engage may had tread on holy land when they apparently used CounterStrike as a promotion for it's in-game advertisement service. Screenshots of what are CounteStrike, coupled with textures in games that are advertisements for real-world companies, can be found on Engage's website. According to Valve, however, that's a very big no-no.

”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.”
The idea of in-game advertising may be no big concern to some, or treachery to others, but it is a viable method for online gaming to find other revenue, especially if the online half of the game is free. However, it of course must be done properly – The exact extent of what, if anything, Engage did wrong here isn't completely clear, but it will be very interesting to follow as it unfolds.