Where I am (not SF) there's definitely a large showing of programmer/climbers at the local gym. I think a large part of it does have to with the problem solving aspect (hell, we call them problems even), but for me it has more to do with it fitting in with my life a lot more cleanly then any other sport does. I don't have to change into a uniform or put on a whole mess of gear or anything of that sort (when I'm going to the gym anyway). I just walk in, put on my shoes, and go. There's no inertia to climbing. There's not many sports that give this; "pumping iron" can but personally I enjoy climbing and solving problems to counting to thirty while sitting in a chair.