Ahkamden - 4:41 am on Apr 17, 2010 (gmt 0)
Interesting..lol my response was from habit. I'm not even sure how WP has changed it's native handling of urls in awhile. I'm a habitual user of All in one SEO. And always seemed to take care of issues. From my post above though, doing some reading before has pointed that Platinum SEO can do 301s.
If you're using built in. I think you'd have to do it through htaccess.