Maybe they are saving that for their Unity3D competitor :)

I really like this theory. Seems to me that if Friday's announcement isn't a game reveal, it'll instead be Source Engine 2 and a possible Unity competitor. This would make a lot of sense if Valve is serious about getting developers on board for their SteamMachine/Linux/cross-platform strategy.

Valve has already announced the OS and hardware, dev tools could be next.

They really like "Steam Machine" off Human After All, and they're looking forward to using it in a marketing campaign?

Strange names are much easier to search for.

Their company is called "Valve" ;)

And they have software named Steam and a game named Half-Life.

The top Google hits for all of those things (depending on how Google rates what kind of consumer you are) are not Valve's products. They seem to do fine, though.