if the prizes is being shipped usps and you have done a change of address you will get them.  If its a prize from ups, fed ex or dhl..and the only info they have is your old address well, then you probably wont get it. unless you get an email from one of them saying its coming and you can tell them of the address change. I would start using the new address to enter as soon as possible.

When I moved, I had very good luck with using Return Path for a change of email address (http://ecoa.returnpath.net/index.php).  Of course, I forwarded my mail to my new address with the post office also.

For everything else, I went through every site that I had a profile with and changed my address and telephone information.  For those sponsors who use your profile information for mailings, it works very well.

Unfortunately, for those sponsors who go by the entry form information only, then you're out of luck for Fedex, UPS, and DHL if the information on the picked entry is your old address.  On daily's, make sure you use your new address as soon as you know it.