[Quiet Man Cometh]

I'd say it's definately rude to be on the computer when one has things to do, but when there is no immediate demand and one is required to merely be present in an area, I suppose it's not too much of a problem. I write a lot and would be on a game forum when I was taking my hour at reception but I cleared it with my boss first. Being normally a data entry and research emplpyee I couldn't do much of the business end of reception but since I was required to sit at the reception desk (on call as it were) and answer phones, I was allowed to do what I wanted at the computer because I was being paid to tend phones and front desk.

One thing to keep in mind about being on the computer is that is shows the professionalism of the employees to the minds of management. My work was pretty lax about it but they would ask that we not leave things like facebook or non work documents visible on the screen in front of customers or regional supervisors. etc.