A new tool, Google Trends for Websites, allows you to compare your website traffic to a competitor’s website traffic.
Coupled with the Alexa Toolbar and other traffic analysis tools, Google Trends for Websites will provide you with a detailed understanding of how your site is performing in relation to other sites. You can compare five sites at a time and the tool provides information about geographical location, other sites visited by users, and search terms used by visitors.
Take a look at it now: http://trends.google.com/websites
