The following PowerPoint file is from the talk which I gave in my research group recently. It is also my understanding and reading notes from a serial of papers by Prof. Udo Seifert, in which he generalized the entropy production on a single trajectory of the small system such as a molecular machine. It mainly addresses three questions:

Sean Carroll at CosmicVariance has an interesting set of slides on the 2nd law of thermodynamics and the arrow of time.  In this age of simulations, one question that came to my mind was whether we could do a molecular dynamics simulation of a glass of ice cubes, allow them to melt, and then simulate the process in negative time to get the ice cubes back.  Probably not.  But the fundamental physical laws do not have any time directionality to them.  So what gives?  More importantly, the universe appears to have had a low entropy beginning but the second law suggests that we are at an entropy minimum at this point in time.