Seth Godin provides an interesting argument for not texting while working (and he differentiates between being at work and working).
For the sake of productivity and competition:
You’re competing against people in a state of flow, people who are truly committed, people who care deeply about the outcome.
You can’t merely wing it and expect to keep up with them. Setting aside all the safety valves and pleasant distractions is the first way to send yourself the message that you’re playing for keeps.
After all, if you sit for an hour and do exactly nothing, not one thing, you’ll be ashamed of yourself. But if you waste that hour updating, pinging, being pinged and crunching, well, hey, at least you stayed in touch.
Raise the stakes.
I see. I think I’ll continue to text while I’m working, thank you. It’s part of my job. Seriously.