Suffice to say at this point there's too much to go in to here, but if there was any way to make the game Portal even more creepy without losing the black humor and so on they've managed to do it this time around.  For the uninitiated:

A recent update was pushed out through Steam for Portal.

The updated included the Achievement "Transmission Received"

Every Portal Test Chamber now has a radio in it.

Moving the radio to a certain location in the test chamber makes it stop playing the salsa remix of "Still Alive".  The red power light turns green and a morse code signal can be heard.

The signal, when decoded, was an md5 hash which when that was decoded, turned out to be an SSTV data stream containing several images: various blurry off-angle shots of Aperture Technologies documents.  On one of them was this phone number:
(425) 822-5251

...which led to a BBS for Aperture Technologies.  When logged in (the login is 'default' and the password is 'default'), the website dumps a ton of ASCII files - some text files, some ASCII art (of in-game screenshots, it is speculated).

Finally, when the aforementioned radios are carried through the 'material emancipation field' (the no-go zone near elevators that disallow you carrying anything other than yourself and the hand-held portal device out of a test area), they let out a weird shriek followed by an almost unintelligible voice saying "get me out of here" (some interpret it as "is there anyone alive there").  Even more creative folks claim that when played backwards it says "...Gordon" (in reference, they claim, to Gordon Freeman, protagonist of the Half Life games, which intersect with Portal in more than a few amusing and creepy ways).  I think they're reaching, though, sort of like "I buried Paul" on the White Album (people will hear what they want to hear).

Anyhow, it's all pretty interesting.  I'd like to do a Portal pen and paper game one day (for folks who've never played the computer game itself which is an unfortunately small sample of people )