I think it's just about Aperture science and the whole backstory there with the HL universe - a little more will probably be revealed on the Borealis in EP3 (or HL3, whatever)
Plus, if you login as username: cjohnson and pass: tier3, you have admin access - but the only thing that i've worked out so far that you can do is 'interrogate' - if you type something after it I think it assumes that it's a name and says 'employee not found' - i've tried everything, gman, freeman, vance, chell, etc; no avail.
==edit, if you type in dir as admin, then notes, you get what seems to be the history of aperture science
Wow this is amazing! i completely missed all this, well spotted im checking it out now
--Edit-- Pah i got to the end of the application and it asked for the 64 digit pin, i thought i copied it down right.......guess not. Well never doing that again
oh ok thanks, haha it comes up with a shopping list or something ah Portal what a crazy game. I love it when developers extend a game beyond the application itself.