Migrate an iPhone from one machine to another

I have three iPhone 4's on my AT&T plan. They all have been synch'd to my iTunes account on my iMac.

This weekend, my daughter purchased a MacBook. Is their documentation on the process for migrating her iPhone from my iMac and iTunes account to her MacBook?

I understand all the content purchased on my iTunes account will have to be repurchased under her iTunes account, but how does this effect the phone plan (if at all).

Thanks.