Here's a summary on the last page, I was idly flicking though when I saw it.
-Portal gets surprise update yesterday afternoon
-People see new mystery achievement
-People play and see the radio in the beginning room now has a green light
-Carry it around and notice it makes strange broadcast interference noises in certain places
-Locate and place all 26 of these mystery radios for achievement
-Smart people yank wav files out of game content folders and run them through steganography programs
-Produces 26 weird cryptic image files in a numbered sequence
-Some dude runs the number string through an md5 hash translator and gets a landline number
-Internet traces it to Kirkland, WA (near Valve HQ)
-People find out its not a phone/fax line but a data line hosting a BBS and telnet it
-Use a clue from one of the files to figure out the BBS user/password login info
-End up with a bunch of weird ASCII artwork
-We're trying to figure out wtf it means
-XJR asks for summary on the forums
I must say, this is amazing work and complexity, it has been speculated that this is the work of the creater of Minerva, a mod for half life 2, who has since been hired by Valve and is well known for his puzzle skills.
Anyways, I'll leave that for the forums, there's the summary.
EDIT: In a few hours they have outdone our longest thread
