The SCiO pocket spectrometer is a pretty neat invention, working with your phone to determine the rough composition of everyday objects by light spectrum. The question is how soon such a device will be standard to embed into a phone. There's already a light sensor in your smartphone: the camera. If the camera can be tuned or upgraded to sense spectrometric data, you might already have everything you need to do the work of SCiO, with the right software.
Mokalus of Borg
PS - I'm not sure how viable that idea is.
PPS - SCiO probably has a relatively sophisticated sensor, more specialised than a camera.