I'm a programmer at a smallish web company. We were, bafflingly, business casual until about a year ago; my jeans got a lot less wear then. It turns out that programmers, as a group, can manage to make any dress code look equally nerd-frumpy. I think of one ex-coworker in particular, who at least once a week would wear the same pair of too-wide-and-cinched tight plus too-short pants, and a silky bright blue shirt with dragons on. And inexpensive dress shoes. There's a point beyond which any dress code short of company-issued overalls isn't going to help.