As a student who is in that dataset, I think it makes sense. Basically, UVa is a pretty preppy school and Macs are really trendy right now. From my friends and what I see on grounds, I'm surprised that the Mac ownership is not numerically higher. We also focus on the liberal arts, which helps Mac. Linux is a real pain to get to work on the network. The decline in "other" is probably in a large part the result of Mac OS providing a very decent Unix/programming environment. I do see CS professors pretty split between Mac and Linux.
I'd imagine that schools that are more engineering focused schools would probably use more Linux, but I would not be surprised if Mac has converted a lot of them as well.
For the record, I had three computers windows, linux, and mac for most of last year, and I was one of the 8 "others" on that chart.
I think you're remiss in not mentioning that UVA has very strong science and engineering programs.
(This is a bit surreal, as I did my undergrad at Virginia Tech, my Master's at W&M, and now my PhD back at Tech. I've never cared for the rivalries, but I didn't think I'd ever feel compelled to defend UVA to one of its own students.)
I'd imagine that schools that are more engineering focused schools would probably use more Linux, but I would not be surprised if Mac has converted a lot of them as well.
For the record, I had three computers windows, linux, and mac for most of last year, and I was one of the 8 "others" on that chart.