I'm surprised to see "platforms" as Win: 41%, Desktop Linux: 33%, Mac: 18.4%. Presumably this question was about the machine you use to develop software on. The reason I'm surprised has nothing to do with any advocacy. It's just that whenever I look around at a non-Apple dev conference in the US (Web, for example), it looks as though fewer than 1/5 of the machines are NON-Macs, while the answer to the question above…
I always get the impression that SO is populated mainly by Enterprise devs using Windows. Edit for spelling.
Although SO now has a much wider audience, the more engaged, longer-term members are more likely to fill out this survey.