Found

iPhone headphone mic works with [late 2008 Mac] laptops

This evening I wondered whether the four-conductor iPhone headsets (headphone plus microphone) could be used as conventional headphones on my computer, nevermind the mic. As it turns out, they not only work on Apple’s laptops, the mic does as well, as does the play/pause clicker. Now you can use Skype without taking off your earphones. (They’re also compatible with almost all of Apple’s iPods.)

Apple’s own documentation is sparse bordering on nonexistent. Product descriptions for their iPhone headsets only mention iPods. The most Apple has written about this is on page 25 of a PDF of the MacBook Pro user’s guide: “Audio out port: Connect external speakers, headphones (including iPhone), or digital audio equipment.

If you haven’t got a compatible laptop, you can make an adaptor that splits into Mic In and Stereo Out plugs, or buy one.