The article is a bit vague and the source is apple itself. Then I am usually sceptical.
It doesn't say for instance which percentage of the employees is using an iphone and for what purposes. If only the CEO has one, you have sold 80 iphones

I can understand that the ipad would have some benefits for sale persons on the road, as it less heavier than a laptop. But still some more accurate figures would be better for the overall credibility