Showing off his still-fit physique, Tom Cruise filmed scenes as his Ethan Hunt character for "Mission: Impossible IV" in Prague on Wednesday (October 6). Mounting the roof of a moving van on a zip wire from the third floor of a local building, the daring actor pulled off his top as he knocked out scene upon scene. As for the new movie, "Mission: Impossible IV" is being directed by Brad Bird with a release date set for December 16, 2011. With few details being divulged thus far, the action flick co-stars Jeremy Renner, Jonathan Rhys Meyers, Maggie Q and Josh Holloway, among others...