Microsoft shipped 9,460 square kilometers of imagery onto Bing Maps. October 2009 release showcases high precision imagery for the USA, Canada and the United Kingdom. The biggest drop by far was Greater Vancouver Metro. You can check full details of release on Bing Maps World Tour application which allows you to sit back and let application give you a guided tour of new imagery; or, you can navigate yourself to see new imager, including previous releases.
More info: Bing Maps World Tour