I see lots of companies starting to see that they can benefit from the fact that so many people are running around with smart phones. What I don't see is a willingness or even an acknowledgement that it might be a two way street. If you want me to use my personal device at work, don't be surprised when I use it to handle personal tasks at work. It's my phone and I'm paying for the voice and data plans, so don't expect me to just turn it over to you for half my waking hours or more. Also, somebody (not me!) better figure out a way to protect the company data that makes it to my phone without having to wipe my whole phone.
If my personal information can't remain safe from your actions and I can't conduct personal business on my own phone, then it's not really my own phone. At that point, somebody better cough up some cash. Or just give me a company phone and I'll leave mine turned off in my pocket or in my glove compartment or in my desk during work, just like I had to do before you 'allowed' me to use it for work.
I heard one fellow put it this way: "I'd give anybody who asks a company smartphone. That means I get an extra 20 hours a week out of them for $100/mo or less. Better yet, let them hook up their personal phones to the company systems and I get that 20 hours a week for free." Hell of an attitude there, and not someone I can respect.