How to redirect to correct pages after permalink structure change

WordPress should handle all redirections correctly, without you needing to worry about them. For example, if your old post was http://example.com/2012/10/11/i-like-stackexchange any links should auto-magically be redirected to http://example.com/favorite-things/i-like-stackexchange. I just tested it on a site with WordPress 3.4 installed, and it worked just fine. WordPress can read your mind.