Check out this finish of the 2008 Mountain Bike Marathon World Championship in Italy this past weekend:
According to this article on cyclingnews.com, after nearly 5 hours of racing, Belgian Roel Paulissen (Cannondale-Vredestein) and Christoph Sauser (Specialized) approached the finish together and tangled handlebars about 70m before the line. Sauser then remounted his bike and crossed the line first, but was later relegated by the UCI officials for riding "dangerously" in the sprint. Paulissen was then declared the winner.
I'm not so sure I agree with that call.