Every mobile phone has:
> LCD screen
> Frequency "conscious" tones
> Assorted amount of switches
> micro processor
The only thing needed to implement a guitar tuner inside a mobile phone would be a little extra software. And there's "room" enough for it.
And NOKIA would have a winner among the millions of guitar/bass/sitar/banjo/violin/cello (you name it) players around the world.
I use my NOKIA for guitar tuning but i have preprogrammed a sequence of tones and then i tune the guitar "by ear".
It would be fantastic if someone could develope the software for it, making good use of the equipment (microphone, screen, processor, etc.)