There is more Portal in the works for you.

Valve has confirmed that Portal 2 is in the works for the Xbox 360 and PC.  It is expected to be out in time for the holiday season.

Eurogamer

Update

Gamestop has details regarding Portal 2….

“Coming this holiday. Portal 2 is the sequel to 2007′s Game of the Year and draws from the award-winning formula of innovative game play, story, and music that earned the original over 70 industry accolades. Portal 2 introduces a cast of dynamic new characters, a host of fresh puzzle elements, and a much larger set of devious test chambers. Players will explore never-before-seen areas of the Aperture Science Labs and be reunited with GLaDOS, the occasionally murderous computer companion who guided them through the original game.”

The price of the game is listed at $49.99.