I was reading Matt Cutts article Switching things around and wanted to note what he said about moving a website.

Matt notes:

changing your IP address, webhost, domain name, blog template, and blog version all at the same time is the exact opposite of what you should normally do.

Changing only one thing at a time is not only a good rule of thumb for SEO; but also, a good way to keep your development cycles simple.

He also notes that a permanent redirect (301 not 302) is the correct redirect to use. A 302 is a temporary redirect only to be used when you might be moving again.