At BloggEd, Ben Yagoda has a pretty convincing defense of sabbatical (under attack in some quarters in light of all the cost-cutting schools are being forced to do because of the economic climate).
He also points out that the anti-sabbatical argument is, practically speaking, doomed:
Still, as I have had reason to say elsewhere, I am not a dummy, and I realize how odd, or even unseemly, it appears when professors are regularly excused from their teaching duties—which are often not killingly onerous to begin with. Nevertheless, sabbaticals aren’t going anywhere for a while. Yet another thing I’m not an expert on is labor economics—but I’m sure that in competitive industries, givebacks are rare or nonexistent. If Lafayette or the University of Delaware or some comparable college announced it was ending sabbaticals, it would have zero chance of beating out its competitors to hire the next top young sociologist or art historian, and slowly but surely the quality of its instruction, and then its students, would decline.