Developer: If it's for a "commodity" programming position (follow instructions, crank out kloc) then maybe it'd be relevant, but those kind of "code monkey" positions are actually pretty rare.
In the vast majority of jobs (IMHO), the speed at which they can write a given function/whatever has almost no bearing on their overall productivity. Most coders only program a few hours a day anyway (see: https://news.ycombinator.com/item?id=8131116) ...it's what they're doing the rest of the time that matters most.
If you have a need to do a timed test, at least do it in pseudocode. That way you're just testing the applicant's logic, instead of how much [php/js/ruby/whatever] they happened to memorize over the years.