I bought this to communicate between my ContourGPS and my iPhone 4, via the free Contour app (downloadable from the App Store).
As long as you don't expect miracles, this works great. It's easy to connect the two: turn the camera on, hold down the "secret" bluetooth button in front of the record switch for a few seconds, release and the camera will beep and the light on the front glows blue, turn on bluetooth on the iPhone, select "Contour GPS" on the phone's bluetooth menu to connect the two, then open the Contour app. This works for me every time without complaint or interruption.
The app is very useful for programming the camera's two settings, and also for framing shots. The image it provides doesn't have a high refresh rate or exceptional colours, but then it is only using bluetooth. However, this effectively gives the little camera a bigger and clearer preview screen than any other POV camera, so for accurate framing it has no equal. Note that the camera turns bluetooth off (so loses the connection) when you start recording, presumably because it's got enough else to think about.
The card is easy to install, effortless to use and adds useful functionality. It very nearly loses one of its five stars from me because it's a shame that Contour didn't include it in the camera in the first place!