Why not post it two weeks ago then, it's not major enough to contact Valve about before posting. The timing just seems a tad bit off seeing this has been in the files since January and two separate people manage to find it only 1 week apart months after the code shipped.
Would be nice if you linked to Pw0nageXD from Facepunch who actually found this first more than a week ago.
http://facepunch.com/showthread.php?t=1260955&p=44092776&viewfull=1#post44092776
All we know is that it's a separate executable (at the moment) that can be given an AppID as parameter. We'll have to wait until Valve releases it to know more.
Streaming is mostly implemented in the current Steam beta build (and working if it wasn't for Valve not shipping the application that does the actual streaming/encoding).
ValveTime already featured that old screenshot of mine in an article last month, here's a screenshot from the latest beta...