I defered at MSUCOM (since out of state is like $40k/year!!). It was pretty automatic once I told them. They know that out-of-state get ripped off there. I sent in my deposit and the MSU graduate/professional school application with a cover letter (which they told me to write) regarding my reasons for defering, which I was up front about, and also gave the reason that a year off would make me a better student for x reasons). I am now trying to find a job at MSU for a year as I need to prove that I'm attempting to make Michigan my permanent domicile.
I think as long as you have a good reason most wont have too big of problem with it. I'm not completely sure of other state schools protocol. Also, before you do it, make sure to check with the registrar's office regarding the state's specific residency requirment. I've heard that some states require 2 years of work in the state. Others, if they know you are working only to gain residency, wont let you gain it that way. Best to check so you don't screw yourself.
-=Eric
