Here's a Google cached FAQ from Microsoft about the technology behind it. <a href="http://webcache.googleusercontent.com/search?q=cache:_b9bZ5U4hMAJ:ftp://ftp.microsoft.com/developr/drg/multimedia/Blackbird/BBFAQ.htm+&cd=2&hl=en&ct=clnk&gl=ie&client=firefox-a" rel="nofollow">http://webcache.googleusercontent.com/search?q=cache:_b9bZ5U...</a>