No, they're actually adding a bunch of new parts to the facility, like the air tubes, the launcher-things, the laser, the lube, the jumping lube, the spikes, etc.
But sadly I heard it was delayed from 2010 to 2011 because of too many fat jokes at Gabe's expense.
Also also, how have you not beaten Portal?
It was like 4 or 5 hours the first time I played it, then once I almost beat it during File Systems class. So like 2 hours.
They even made it free that one weekend. A WHOLE WEEKEND. YOU COULD HAVE BEATEN IT LIKE 5 TIMES.
Edit: Gameplay videos I watched. Pretty psyched about the laser and the lube.
http://www.youtube.com/watch?v=rt6SeY-7FWQ,
http://www.youtube.com/watch?v=BQLl6UiNxF4,
http://www.youtube.com/watch?v=Rkp8QO_PJ0s
Also there's going to be a sphere with a British accent. The bad kind, though. Like the "Fuck, stop talking" kind. Hopefully they'll cut him out before release.