I do consulting work with scientific and engineering firms and I'll contend that it still largely holds. For me, the trick wasn't to look at how the engineers dress. Rather, it's how management dresses and they tend to adhere to moderately strict rules for dress. At the end of the day, they're the ones that sign my contract, so it's important that I communicate to them that I understand their rules of conduct.

In case anyone is interested, Alan Flusser's book, "Dressing the Man: Mastering the Art of Permanent Fashion," provides a good background on the history of men's formal dress and why certain things are the way they are. Certainly, we can disagree as to whether it should be important, but clothing is a language, so we might as well understand what we're saying in a particular context.