News.com reports that Dave Schroeder, a systems engineer at the University of Wisconsin-Madison, proposed a challenge to hack into a Mac Mini that he attached to the university network. The challenge was to last until Friday before administrators pulled the plug on Tuesday. Dubbed the “Mac OS X Challenge,” the contest ended without any negative impact on the university’s network. The target computer was connected to the Net for more than 30 hours without being compromised. This challenge comes on the heels of two worms have raised questions regarding the security of OS X…