Cool thing but the main issue is that people actually love getting a new phone and playing with it.
The queues outside an Apple store on launch day etc.
Can see it having a market tho, but not because people are interested in saving the planet, but more because it will be a talking point down the pub!
I've had the same HTC Desire since it first came out 3 years ago and it's only my 4th mobile phone since 1996. I definitely don't feel the need to rush to the shops every time something new comes out and would LOVE the option to replace/upgrade parts on an old one. Not because I'm trying to save the planet as such, just don't see the need to get a new one when I can get by fine with the one I have. Pity, because it's unlikely this will ever take off.