The Yale project on climate change communication released a working paper, a reader of this blog pointed out to us, that examines the impact of Climategate on public perceptions of climate change and climate scientists, drawing on a national survey which was conducted in December, 2009 and January, 2010.
In brief, the project found that "Climategate" had a significant negative effect on public beliefs in global warming and trust in scientists. The loss of trust in scientists, however, appears to have been primarily among people with a strongly individualistic worldview or politically conservative ideology. Nonetheless, the project found that Americans overall continued to trust scientists more than any other source of information about global warming.
You can download the working paper from the project's website.