FWIW I just viewed source at http://wordpress.com/ and I didn't see anything similar. However I have heard Matt Mullenweg mention that they hide messages for people reading through the wordpress source code.
It reads something like this:
"If you're reading this, you should visit automattic.com/jobs and apply to join the fun, mention this header"
I got this when I was sniffing my own network packets while browsing wordpress.com lol I was trying to demonstrate BREACH attack back in summer....