From Lost Garden: Convergence: A great word to hate:
By this argument, if the technologists had managed to figure out how to pack a camera into a standard keychain (and people were constantly encouraged to upgrade their keychains), the "camera keychain" would have been nearly as successful. The customer value is what matters. The fact that the value takes place in a convergence device is mostly random happenstance.

I'll take exception with that. The cameraphone is an issue of convergence insofar as the phone uses a small, high-resolution (relatively speaking), color display and the camera benefits from the same. There is also some overlap with taking pictures and sharing them, from the screen, of course, but also via email or uploading to the web. So networking on phones is somewhat important as well, at least for those whose plans already have digital services (or those for whom the camera puts that purchase over the top).

There is no networking, no screen on a keychain or wallet or other pocket device. Adding the camera would mean one has to add the entire camera. In some respects, the cameraphone works because over half the camera is already in the pocket.

Now I usually go into some sorry talk about how it's the shared binary medium and generalized computer processing platforms that allows this overlap to happen (see the camera-radios of the early twentieth century. A bit more fadish), but I'll spare you that today.