Just say the words "bring your own device" and IT staffers start to rub their foreheads. Allowing users to attach their consumer devices, including smartphones and tablets, to the network might seem like a bad idea, but with a clear user policy that is re-signed annually, you can reduce a lot of organizational risk.
Make sure to include language about which platforms you support, whether or not you reimburse for various charges, what state the device must be in (i.e. not rooted or jailbroken) and what applications can and can't be used while on the network.
Here are a few samples of BYOD policies to help guide you. For a longer discussion of BYOD policies, check out this white paper from the SANS Institute.