At my work, we're interested in tracking how often people print our web pages. (If a lot of people are doing it, we'll probably put more focus on making the print view nicer.)
Obviously if we put a "Print" button on the page, we can log when people click on that, but if users just use the "File" menu and choose "Print," we have no way of knowing if they did that.
Is there some clever way to use print-only CSS to cause the browser to issue a web request only when printing? My experiments seem to say no, but this seems like it should be possible.
Edit: A reasonable answer is offered below that works in FF; I'm offering a 100 point bounty for a solution that works on IE as well.