Purchasing Iphone 4g, Should I restart my Jailbreak on my 3g before going to Apple

[amicone18]

I'm camping out 3 hours before open at Apple for the 4g, I have a 3g right now. would I need to restart to factory settings before switching at the register, I dont know if an apple rep takes my phone and switches the sim card and such. Is it not a good idea to have the phone you plan on switching jailbroken?

[iop9000]

You will get a new sim card (microsim) yout old sim
will not fit on the new iphone4