Unlike Firefox and IE, there is no way to tell Safari/webkit to open links asking for a new window in a new tab in stead. This is a major inconvenience. Is there any reason why such a feature cannot be implemented?
Tabs are a feature of the browser application that makes use of WebKit, not of the WebKit engine itself. See <http://webkit.org/blog/101/back-to-basics/> for more information. Please use <http://bugreport.apple.com/> to request enhancements to the Safari application.