It probably wont have a multiplayer, being purely a puzzle game (from the looks of it), but the portal gun may be implemented into Episode 2 and later Half-Life titles ^_^
I suggest watching the trailer off Steam, since its full screen + high quality. And it pwns. http://www.steampowered.com/index.php?area=news&id=693
This game looks truely brain-wrenching. I want. Now!
