I especially like the explanation provided in the comments: "This was done as a passive-aggressive motivation to get someone to create the linux close/min/max/restore buttons, I believe. And the message got through, and the work was done. ;)"

I think it was celebration, the Linux UI changed recently, Glen's face appeared yesterday :)

I posted it on my flickr too: http://www.flickr.com/photos/igorgue/3789856159/ along with a chat log on the IRC channel.

Maybe the head is there to symbolize that big brother Google is always watching you???

Definitely belongs to reddit. :)