When you get an iPhone, you can download and install "Good for Enterprise"for free. this gives you basically the same security as RIM. you can also wipe the device remotely from admin console. All data is encrypted. you can set limit for each users or group base on their device type, os version, user group...etc..
I have been usinf BB for years, since last week I have switched to iPhone (I was forced to do so as VP-IT request to test it for our executives). I shall say it is not bad at all, to be honest I like it a bit more than my all other BB's.
cheers