Two things off the top of my head:

1. Cellphones that are fingerprint encoded for security i.e. the phone will only unlock and function when it has scanned the owners fingerprint maybe at the back of the phone…instead of a pin if you get me…you could also use the same feature to scan other people’s fingerprints and have the phone do checks on them or positively identify them

2. I would love to see glasses becoming an interface for cellphone i.e. a pair of clear glasses or sunglasses that wirelessly connect to the phone and one eye’s lens can act as a screen and you can see your screen display…that way you can text while your driving and look at your GPS map while your driving too….there are plenty of things still to come with mobile phones and I think what we have right now is just the tip of the iceberg, after all the mobile phone is the one piece of tech nearly everyone owns and always have with them, so its just natural that most technology will develope in this field