Up until mid April 2010, Google Webmaster Tools showed a list of top search queries for your website, and there was no way to figure out how often your site appeared in Google searches, and how many times people actually clicked on your site's link to get to your landing page. Fortunately, this valuable SEO data is now available! Newly introduced feature (on April 20, 2010) in Google Webmaster Central allows to see how many search impressions and clickthroughs your website actually gets under the list of search keywords related to your website. Google also shows a list of your site's web pages that are linked to from the search results for a particular search query.
We do not know how accurate this new data is at this point, but SEO professionals, including ArtDriver, are doing a number of tests to figure this out. In any case, having a new set of search engine optimization data from Google is going to be helpful for site owners and SEO gurus. The new statistical information on impressions and clickthroughs can help to optimize conversions. Knowing what one's clickthrough conversion rate is, is a whole new set of data that we never had before.
To register your site with Google Webmaster Tools, go to www.google.com/services.