RIM isn't just bloody push email!
The security features on a blackberry are outstanding, software profiles prevent employees installing unwanted potentially dangerous 3rd party unvetted software, the lack of a camera is also seen as a plus for companies where security is paramount. if someone does lose a unit they can be remotely wiped, and wiped, and wiped, i think i recall the data is overwritten 8 times when a command is sent for it to selfdestruct.
The smartcard product available is also very elegant, if your unit is more than a couple of metres from you it locks up.
Even the much publicised 'security-hole' was just a media frenzy - it relied on a chain of events which starts with the very very unlikely scenario that there won't be a company wide software profile in place, ie. users would be able to install software that reaches them through a malicious email.
Compare all this with a pocketpc powered device...