After our successful modding of the Creative Fatal1ty Gaming Headset for use with the iPhone, I realized that there may be others interested in the pinouts for the iPhone headphone plug. I've seen other places that mention the external iPhone plug functions, but to do anything productive you need to know which colors go to the plug itself.
What are the iPhone headphone plug pinouts?
Green is 1st contact/left headphone
Red is 2nd contact/right headphone
Red/Green Combo and both coppers are 3rd contact/ground
White is 4th contact/microphone - the white wire is inside the red/green combo wire
If you would like for us to mod a headset for you, leave a note in the comments and I'll get back to you. The process should work with any headset that uses the 3.5mm plugs for input and output. It is just a matter of determining what the wires do in the headset itself.
I also found that the Verizon stores carry a 3.5mm to 2.5mm adaptor for US $3.99 - it has the same pins in the same positions, though I haven't tested it. The Verizon adaptor option is way cheaper than destroying a US $29.99 pair of Apple iPhone buds. If you try it and it works let me know and I'll update this post.