It's been less than 24 hours, and fans of Valve's first-person puzzle game Portal have already deciphered what the new achievement is and many of the radio messages. The achievement is to find the radio in each level and take it to an unknown spot, where it will spit out a transmission at you. Those familiar with ARGs - or Alternate Reality Games - will be instantly familiar with what Valve is doing, and the video above shows just what the radios are transmitting: images.

SSTV, otherwise known as slow-scan television, is a way for amateur radio operators to send images over the radio to be decoded by the recipient. These images often have some corruption, as they are transmitted at a much slower bandwidth than traditional images or TV. In most cases, these images are things like local scenes, but in Valve's case, it's hints at things in the Portal universe. Specifically, the images seem to be forming some kind of code. For what? We don't know. More as this develops, and you can track progress yourself via the Forum thread.

Update: The code in the images apparently leads to the Kirkland-based land-line (425) 822-5251. This number is modem that leads to a BBS.

Update 2: Do not call the phone number, as it ties up the connection and makes people unable to work on the ARG.