There’s also an expanded ending now.
I haven’t clicked on that link because I don’t want it spoiled, so if it explains my proceeding question, forgive me.
Do you have to replay through the whole game to see the new ending or can you just rebeat the game from an old save late in the game?
Other people have claimed that all you need is one level load between your save and the ending. So if you still have your old saves you can get it by going back to the level before Glados. The ending is only very slightly different. If you don’t have a convenient save the youtube video should be fine.
For those interested in reading the GameInformer article, I have come across scans of it here, towards the bottom of the first page of the thread, hot off of a charitable fan’s scanning press not more than an hour ago:
http://palgn.com.au/viewtopic.php?p=698170
Get them while they’re still hot. Because hot stuff usually gets taken down! 
I am eagerly awaiting this. Portal is the only game in the last ten years or so that’s even tempted me to go back to Windows, and I’d love to be able to play it on my own computers.
You will also then be very pleased to know that the GameInformer article I linked to in my post above states that Portal 2 will also be released for Mac as well. 
P.S. I should probably add that the article does have a lot of narrative spoilers but I can’t help eating up this info! Part of what made Portal such a great surprise was that there were few expectations and not much information about the plot … now all that’s going out the window but I must say I absolutely LOVE the direction they are taking the story from what is mentioned in the article.
Also this …
GameInformer is hosting a dedicated section for Portal 2, and will be unveiling new material every other day or so for the rest of March. The first post in the section was basically the reveal of their April cover exclusive, so I suspect that the eleven remaining reveals might simply be the remaining pages of the article (it was basically eleven pages in length). We shall see.
Put me down as disappointed. I liked Portal and I’ll definitely play the sequel, but my patience is starting to wear thin for a completion of the HL2 story. Not a cool cliff to leave us hanging over for years, Valve. :mad:
This is what happens when you have a game made by rich perfectionists that will be the sequel to what’s widely considered to be one of the best games of all time.
Slight update for those who missed it: Gabe Newell accepted the “Pioneer Award” at GDC 2010 on Thursday and gave an acceptance speech which addressed aspects of Valve’s approach to product development, in particular their approach to announcing a new product by embedding clues within a previous product and allowing the fan community to interpret them. Towards the end of the speech, just as he was about to go into more detail on Portal 2, the presentation stopped working and then went blue screen, displaying the following BSOD message …
Those in the community observant enough to realize that the error message was in fact comprised of hex codes, cleverly deciphered the error message characters to arrive at the hidden message “SUSPEND UNTIL EEE”.
It would seem that Glados insists on holding off any footage until E3 in June …