Half Life viral marketing clip?

This clip has been out in the net for a quite a long time, it's some kind of viral video.
It still isn't clear if it's something official and what purpose it has, but apparently it wasn't for a possible HL2: Episode 3 announcement at GDC, since the convention is already over.

It's really well done and i can recognize all of source sound, but.. what's that cube?
Portal maybe?

Also, the soundtrack is from the Lost TV series. Odd.

There's a link on the info, but the site doesnt say much.

Well, i guess we all have to wait, won't we?