The comments on the paper in the Times were terribly poor and simplistic (many of them by people who had clearly not read the paper, or had not really understood the view presented in it). However, a very interesting discussion on the paper took place at the web of the On the Human project.
McMahan has also written a response in the Times in which he explains in more detail the kind of view he has been arguing for.
Many blogs and sites have started to discuss the paper. Some of them just want to attack McMahan. This happens, for example, in the case of the anti-animal rights and speciesist blog The Unvegan, in which McMahan is portraited as “a villain” (together with others who criticize the discrimination of nonhuman animales).
However, many other sites have tackled the issue seriously. For instance, you may be interested in taking a look at the following ones: