vanessafox - 1:52 am on Mar 6, 2011 (gmt 0)
To answer the question about when Google has asked for feedback before, they're always looking for feedback. As I noted in my Search Engine land article, one of the primary reasons we created the webmaster trends analyst position was to look for feedback across the web on these types of changes. But Google also asks for feedback formally every so often.
Matt Cutts opens comments up for general feedback all the time, as you can see in this post:
Note that Google used to ask for feedback via their contact form or Matt's blog before we created the webmaster discussion forums.
And Google solicited public feedback on both Big Daddy and Caffeine: