I've put together a short blog post on how to add tooltips to pushpins in Bing Maps V7. This is meant for those who want a simple hover over tooltip to occur when hovering the mouse over a pushpin. You can find the blog post here:
http://rbrundritt.wordpress.com/2011/11/21/pushpin-tooltips-in-bing-maps-v7/
http://rbrundritt.wordpress.com
