According to Maile Ohye, today's keynote presenter at SES Chicago 2010, not much has changed with the introduction of Google Instant.
Impressions per query has gone up considerably, on the order of 5-7 times that compared to "non instant," according to Ohye. Translation: webmasters that see a decrease in CTR can probably attribute part of that drop to Google Instant "impression flipping."
Every week, Google's webmaster trends analysts team gets together to talk about how webmaster's are reacting to Google. This includes the biggest complaints found on the forums or on blogs, bugs spotted and much more. Maile said, since Google loves to use math to measure everything, the team developed a "Webmaster Happiness Metric," which they use to measure if webmasters are happy with Google or not. They hope to come out of every meeting earning a higher score than the previous week.
In addition, Ohye shared details about the development of a new "rel=alternate" tag for websites with multi-lingual site templates. And another particularly useful e-mail alert feature from Google Webmaster Tools that alerts you to potentially unsafe pages on your website (malware, phishing, etc).