Portal is Still Alive (Haha, get it?)
Fresh off the E3 presses (that show that no one cares about, right?): more Portal is on the way.
Information is scarce right now, but the sum total seems to be this: It'll be released for the XBox Live Arcade, instead of as a boxed game. I think it's assumed the game will also come out via Steam, but I don't think there's any super-official confirmation of that.
This second title, called "Portal: Still Alive" (Try Googling that to get some information. Is good time, yes?) will be a "continuation" of the original game, and include a "new challenge mode".
As Kotaku astutely notes, we were told in April 2008 that we "won't see a new Portal this year". Since this new game is slated for release in 2008, it seems there have been some crossed signals.
I have googled a bit and found this and this
No doubt they will release in for PC, though, the information are still only about Xbox, which is frustrating for us, PC players, at the moment.
(percentage calculation sphere self-test failed!)
108.1% done, -8.1% remaining...
Released here!
All maps for Portal (1/2) worth playing are mirrored here.
No doubt they will release in for PC, though, the information are still only about Xbox, which is frustrating for us, PC players, at the moment.
Right? But however Portal for the Xbox is all you get. You don't get extras like you do in the computer. I have both versions of The Orange Box so I don't have to worry... It will make me play Portal for the Xbox again since I got the computer version for my birthday.
The more you give, the less appreciated it will be received.
Why are you even discussing the idea that it might not be released on PC.......... how dumb can you get!?!
Valve makes games for PC, then thinks about releasing them on other consoles.
End of discussion 
It's not Portal 2 but rather just more puzzles (chambers maybe some BTS) and a new challenge mode. So it's not an entire sequel but rather just some add-on levels. It *could* just be for the XBOX since they can't download any user-created maps but I highly doubt Valve wouldn't also release it for the PC since it would be very easy to do.
According to this page...
So it looks like it will just be a separate, stand-alone version of Portal with a new challenge mode and probably some bonus maps.
I agree.I remember someone saying that Portal 2 won`t be Portal with different colors.And i think it will be an expansion,really why to announce a game that is just a bit modified version of Portal?It is pretty big announce for a such small update...
Considering the XBox uses directX 9 I would imagine it will be ported over to PC shortly after release, either by Valve officially or someone in the community. It's not really a big deal to me, we've got tons of great custom maps right here at TWP to keep us entertained.
how much did you get paid for that advertisement? 
yeah but seriously. we got good stuff. atleast 2 good portal map packs. and MANY good individual maps. plus our community map project that may see light someday. regardless. UNLESS this is just like a map pack that valve put together, or peiced together from user maps. i seriously doubt it would be xbox only. but if it is just new maps without alot of new concept then they might, cuz they know that we (the pc users) would unlikely pay $19.99 (usual single game price) just to get maps. when we got ALOT here online. if there is more to it than that, i have no doubt they will release it on pc too i mean if nothing else. a steam release doesn't cost them much in the way of advertising, production, etc. since most of that will already have been done via the xbox release.
Awwww i taught it is a sequel...Oh well,any new content,if not released,will be ported to pc for sure.
Come to think of it I actually paid for that advertising (see Supporter title), hehe. I read the release a little closer and it does say it's an xbox exclusive for 2008, which may mean the PC release will come in '09. Wonder if they'll bundle it with Portal 2, like an Orange Box 2?