http://www.steampowered.com/index.php?area=news&id=372

To quote:
"Half-Life 2
* Solved disc in drive incompatibility error by removing Securom disc check routine"

It was bugging me that valve (or maybe vivendi?) was insisting that the retail version included securom to enforce a physical media check when launching the game - all the while allowing the online (steam) purchased versions to not have such a check (for obvious reasons).

I wonder, was the presence of securom a test of sorts to help guage the effectiveness of steam's DRM against physical media security techologies? I expect that somehow it will come up durring a talk at this years GDC, probably as valve tries to pimp steam to game developers.

But now that the stupid check is gone, all I can really say is: Finally.