I'm using a Turtle Beach Z11 PC/iPhone Headset with my Elecraft KX-3, this headset terminates in an iPhone 4 section 3.5mm plug and allows use like that in the iPhone.
Using the Turtle Beach supplied PC splitter adaptor lead, this 4 section iPhone plug is converted into two 3.5mm leads one each for microphone and speakers for the KX-3/PC and works great.
I've just tried my iPhone white microphone/earplugs into this same adaptor with my KX-3, it does work!
Receive audio is fine, transmit audio is OK but I can hear a liitle bit of electrical interference in the shack whilst monitoring my own transmitted audio. Looking at the white lead being so thin, maybe this is due to less shielding than the thick cable on the Turtle Beach headset which exhibits no such noise?
73 de Philip G0ISW
http://www.qsl.net/g0isw