Um, this article... is not about bluetooth. It's about the wireless headsets for phones, like the one I have next to me by Plantronics. It hooks into my Meridian/Nortel phone.
Bluetooth uses some basic encryption and digital signal processing, so the equipment needed to eavesdrop on it is quite a bit more complicated than the off-the-shelf stuff this article describes.
And the title of the thread is... dramatically incorrect.