New line in robots.txt disallows results like:

http://www.google.com/search?q=site:google.com+inurl:websites%3F+-groups&hl=en&rlz=1B3GGGL_enUS269US269&filter=0

I think it probably is for the new Google Trends for Websites (trends.google.com/websites)

it appears both www.google.com and trends.google.com share the same robots.txt file

Ahh... maybe?

Definitely.