Managing your brand environment is one of the critical steps in the thrid phase of the personal branding process - Exude - and items such as pens, diaries, computers, cars, offices all say something about your brand.
Cellphones are fast becoming an all in one item - phone, camera, MP3 player, diary, e-mail, web browser, TV etc etc. So it is even more critical that the phone you choose is on brand for you.
The phone manufacturers are getting in to this in a big way - colours and faceplates have been around for a while obviously, but now you can also get charms that light up when the phone rings, vaious styles of cases, sequined stickers and even custom labels.
William Arruda the personal branding guru has talked previously on his blog about your brand being determined by both your phone Ring Ring...... and the ringtone that you choose, as well as your laptop - Brand Your Laptop
So whether its the latest Blackberry, or two cans of Coke connected by string - just make sure its on brand.