Goodness, that happened with absolutely no fanfare. The original Portal, if you somehow don’t already own it, can now be installed and played entirely for free via Steam. I’ve just checked it on a spare Steam account myself, and it works just dandy. This is true of both the PC and the Mac version, by the way. If you’re determined to pay money for it, you can still cough up for The Orange Box or the Portal 1+2 package, but just Portal itself now defiantly costs no-pennies. Grab it from here.

(Big thanks to all who mailed about this)