I think I'll explain how i made my ingame pic:
1) Found a CS:S map where there was a spot with 0% lighting.
2) Opened up the console. Saw a bunch of CS:S stuff in it. /cleared it out.
3) Typed the commands you saw.
4) Fixed it up in MSPaint. The fonts ARE correct (except for the W in NEW because there was no W in the pic... I inverted an M). I also erased the "Connected to localhost on map blah" line in the upper right., and erased the CSS logo in the middle of the screen (I could have pulled the HL2 logo from the Source SDK and applied it, didn't feel like it tho). I also made the picture knowing about the HL2DM rumor and decided to make it look as if the rumor was true (I hope it is!).
5) Found a good HL2 screenshot in the first few results of a google query. Probably shouldn't have picked the next one in the series from Jim's hehehehe...

6) Fired up the GIMP, overlayed the two images with a 75% opaqueness on the console shot. Exported to JPG. Resisted the urge to put "Haha *****" in the image comment.
Easy.
[Edit: grr p w n e d is starred out... ?_?]