Sequel to award-winning first person puzzle game due this year
Valve has announced Portal 2 will arrive at Christmas.
No platform details have been revealed, although the use of the word 'shipment' in the press release implies a retail launch.
The original Portal was made available in The Orange Box, and won multiple game of the year awards. A Xbox Live Arcade version, Portal: Still Alive, was released the following year.
http://www.mcvuk.com/news/37869/Portal-2-announced
