Microsoft using WebKit for their Bing PagePreview feature?

Just spotted this in my web server logs:

X.X.X.X - - [02/Jun/2012:11:25:45 +0300] "GET / HTTP/1.1" 200 371 "-" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534+ (KHTML, like Gecko) BingPreview/1.0b"

Is Microsoft now using WebKit instead of their own code?