It's definitely true that you don't really need to do much to get bluetooth audio on any pair of headphones or earphones. Many bluetooth receivers exist that serve to fill this niche. However, most of those receivers require you to plug in your headphones using the audio cable already attached to them, which means you'll have to either suffer the length of cable dangling around uselessly - negating the benefit of bluetooth in the first place - or find a way to hide them, which is not very aesthetically pleasing.

This mod allows you to gain the benefit of bluetooth without the hassle of wires. Admittedly, it's not a very original hack, but my take on it forgoes the use of cables entirely - except for a very short length that's used to bridge the tip and ring terminals in the TRS audio plugs. It will work on any pair of headphones with removable audio cables, and any battery-powered bluetooth receiver with audio-out. You can be very flexible with the hardware here.

Note: I am aware that there is an existing product which offers the same benefit as what this mod aims to accomplish. The BTunes looks like a very neat little device, however at $79.99 (pre-selling price, it will be $99.99 once production is complete) it's quite an expensive solution. Also, you don't get the bragging rights of having DIY'd your own little adapter.