This has left many webmasters confused with a sudden escalation in visits and page views but also an increase in bounce rates and conversion drops.

To help bring calm to webmasters and analytics users, Googles John Mueller posted this on the Google Analytics help forum:

Were working on a solution for this, to prevent Google Instant Preview on-demand fetches from executing Analytics JavaScript. Im not sure about the timeframe, but Ill drop a note here when I have more to share. Thanks for your patience.

If you are using other website metrics tracking solutions, it might make sense to also filter that user-agent out (the detailed user-agent is listed in the FAQ page).

Google have announced that they have fixed this problem and webmasters will no longer see the visits from Instant Preview in their Analytics account. However, Google will not reprocess the existing data to remove past visits, but is offering users an advanced segment where they can see the visits from Instant Preview in the context of their total traffic. If you wish to clean up your data, Google suggests the method outlined here.

Have you noticed a change in your analytics data as a result of Google Instant Preview?