motorola usb->3.5->headset: compatibility?

[arne anka]

hi,
the other day i saw from motorola an adaptor changing a mini-usb into a  
3.5(?)mm headset jack.
http://www.amazon.com/Motorola-3-5mm-Stereo-Audio-Converter/dp/B001A1IKFK/ref=pd_sim_cps_1_img/002-7641246-5084844
does anybody know whether it works with motorola phones only?
if not, it easily could solve the issues with audio jack of the freerunner  
(whose impact i still fail to understand).