So since this is on slashdot, I'll just copy what's there.

"It appears Valve has begun another ARG (Alternate Reality Game) similar to the one that led up to the release of the original Portal game. A recent Portal update unlocked a new achievement which has uncovered various hidden images and sounds containing references to the Portal and Half-Life universe. Many believe this to be part of the run-up to the announcement of Portal 2 and/or the next installment of the Half-Life series. A thread on the Steam forums has already reached over 1 million views ( ) as people piece together the information. Another thread summarizes the information found so far. Based on clues from the ARG, some are speculating an announcement at the 2010 Game Developers Conference where Valve's co-founder Gabe Newell is to receive this year's Pioneer Award."


The summary thread is pretty good.

Quick summary - apparently the static noise in the new radios in the Portal game were run through Slow Scan TV programs, and the image produced was

http://i49.tinypic.com/s4b7zn.jpg

The numbers led to a BBS

The BBS had more images on it, one of which was

http://farm3.static.flickr.com/2801/...b95fd393_o.jpg

and

http://dl.dropbox.com/u/116597/Portal/human.png