Obama has had a Blackberry for years, since well before he became President. While the platform is secure, his device(s) had to have an extra layer of security built in before he was allowed to use it on official calls. The NSA has built very advanced encryption and code changing into the existing RIM features. And Obama doesn't use one Blackberry, but several (randomly). So it's not as if the Blackberry, off the shelf, was sufficient for the job.
Interestingly enough, the PM of Norway used an iPad to run his government after the volcanic eruptions last year.
You're right that security is important. But as was detailed above, back office support can and does add extra security to the company's liking. An aerospace company and military contractor that I had an affiliation with is now allowing iPhones on its network (as well as Blackberrys), and a slew of iPads showed up in the engineering dept. late last year. This is the same operation that forces people from other company divisions to give up their cell phones at the security office if those phones are equipped with cameras. But those employees who agree to have their iPhones on the network have some sort of software/app installed so that the phone can be remotely wiped clean if it is lost or stolen. When I was there, a laptop was stolen and you'd have thought the world was about to end. So given how RIMM is now losing enterprise marketshare, it seems that some companies are balancing security concerns with how capable the device in question is.
