‘Cell Phones at Work’ is right about a few things, but it all depends on where you work. A friend of mine has a job where his boss doesn’t care how much he uses his phone (as long as he still gets his work done).
At my job a cell phone is strictly forbidden. If you are one of the ‘naughty people’ to have one (like myself and almost everyone else) then you have to keep it hidden away in your pocket.
As long as people are not using it all the time then I don’t see a problem with having a phone at work.