I've made a quick search, but I don't think it's been mentioned yet.
Yeah, ok, so there's a thread about Portal, so ordinarily it wouldn't be worth making a new thread about the game's website. But see, that website is a little special. Take a look:
www.aperturescience.com
If you type "help", you receive a message. I assume there are other commands like that, but the most interesting one is "login", which allows you to, well, login. At that point you're asked for a username and password, the username doesn't seem to matter, and if you give the right passwork you can actually access a sort of "DOS-like" environment.
So get started exploring and report you findings here.
Also, if mods believe it should be merge with the original Portal thread, or sent to the place of laughs and games, or whatever else, then please do so. As if you needed my permission.
Jam it back in, in the dark.