Several weeks ago I was put on blackberry for work. I thought I'd use it for a few weeks before replying to this topic. My overall thought is actually very similar to my original post on this topic on June 25.
The ability to send and receive email, sync contacts, calendar and documents on the go certainly offers a level of convenience that we did not have five or ten years ago; I think this capability offers an even higher level of convenience for a freelance stage manager who many times does not have one central office location outside of home. Phones with a GPS feature combined with google maps could be incredibly advantageous to a touring SM or Company Manager (or to anyone on tour, for that matter) or when working in an unfamiliar location. Is having a smartphone a necessity? No. Does it make the job easier? In many ways, I think it does.
Undoubtedly there are a multitude of potential pitfalls with a smartphone. I have been on the receiving end of many emails sent from a blackberry where it's painfully clear that the sender was either distracted by something else or did not fully comprehend the email to which they were replying. In these cases I think a smartphone does more to hinder communication than foster it. Also, the physical addiction has been mentioned in several previous posts.
Pitfalls aside, it is clear that the smartphone is here to stay. In my opinion the key is, as with any piece of technology, to use it not as a crutch to stand on, but as a tool that aids us in doing our jobs.