On March 1st, 2010, a first update was made, with the description "Changed radio transmission frequency to comply with federal and state spectrum management regulations".[3] It consisted of an additional Achievement, "Transmission Received". Playing Portal reveals the game now has a total of 26 radios (including the ones already present before the update) playing in the Test Chambers, always in an area more or less difficult to reach (but given to the player by the music playing), and with a red sprite added to the switch. The radio transmission frequency is also said to have been changed, "to comply with federal and state spectrum management regulations", as said in the update. In-game, the radio must each time be moved in a particular spot of the Test Chamber. When doing so, the music will be scrambled by interferences, then Morse code or data transmission sounds will be heard, and the red sprite will turn green. To be made in each Test Chamber, finding all radios and jamming the transmission will unlock the new Achievement, "Transmission Received", although its description is simply "..?". The presence of these new radios seen through the Enrichment Center are likely non canonical, as they only serve a viral campaign. They may even be removed when their purpose is achieved.
Thank you for assuming the party escort submission position.
http://half-life.wikia.com/wiki/2010_Portal_updates
The speculation is that this is leading Valve to some big announcement at the GDC on March 11th.
Oh, and a funny sidenote about the new ending, if you play it yourself and noclip, the robot dragging you is a box of beans.