Half Life 2:Portal patch comes through the radio
Valve released a patch for Portal on Steam and the patch notes only say "changed radio transmission frequency to comply with federal and state spectrum management regulations." That would make sense, except computer games, like Portal, don't transmit anything via the radio. The patch notes caused the Steam forum to speculate and eventually find out that Valve added radios to each level in Portal. The problem is that each radio has to be carried to a specific area in game to "tune in" and receive special coded messages. If you manage to get all of the Portal radio transmissions, you will get the new achievement "Transmission Received."
Some of the Half Life 2: Portal radio messages range from the technical ("External data line active") to silly ("Beep Beep Beep") to encoded mathematical messages ("B.dA=3"). It all seems to point to the fact that GladOS managed to transmit herself outside of the Aperture Science lab before Portal ended. There has already been hints at a sequel to Portal, but hopefully this Portal radio patch means concrete information on Portal 2.