Google added the following line to their robots.txt file:

Disallow: /reviews/polls/

Anyone know what this is for (or could be for)?

It's for the Blogger polls feature described here:

http://buzz.blogger.com/2007/07/polls-out-of-draft.html

Looks like they want to exclude them from the results...

e.g. http://www.google.com/search?q=site%3Awww.google.com%2Freviews%2Fpolls

Hmm.

/reviews (Expert reviews)
/reviews/search (User reviews)
/reviews/polls (Blogger polls)
/reviews/w (Edit results)
/reviews/y (YouTube Annotations: http://www.google.com/reviews/y/read?videoid=SzEvcS01Cl0)
....