Apple’s $79 In-Ear Headphones with Remote and Mic are a lot more comfortable than the headset that shipped with the iPhone 3G. So, although it was designed for use with the second and third generation iPod touch (and late model iPod nano), I bought it for my 3G. The headphone, mic, and pause/play worked as expected. However, the volume control did not work with the 3G. I’m happy to report that the In-Ear Headphones features, including volume control, works with the iPhone 4.
If you are wondering, the volume controls do not work with the 3G even after upgrading it to iOS 4.