Moving from MovableType to WordPress involves a bit of fiddling about with redirects. How much fiddling you need to do will vary on your setup. In my case my MovableType URL structure was based loosely on a WordPress one, as I'd migrated from WordPress to MovableType previously.
Of course if things were that simple life would be a lot easier - and probably a bit more boring
I won't bore you with the details, but suffice to say that "simply" redirecting a couple of things wasn't going to work for all posts .. ..
A couple of plugins that helped resolve this (assuming that it is actually resolved):
Redirection - a very powerful suite that logs 404s so that you can redirect on a per page / post / file basis or setup a solution to catch all the issues
Permalink redirect - handy if you need to update your permalink layout and don't want to lose traffic to the old links
For some reason, possibly the settings I had in my MT install, all comments were set to off on the imported posts. This post has a lot of handy tips on opening comments (or closing them) using MySQL ie. directly running queries on the database. A single SQL query is a lot faster than manually updating hundreds of posts!
WordPress SEO - helps with tweaking your WordPress powered site to maximise the SEO impact
WP Super Cache - One of the things I love about MovableType is that you can set it up to write static files so that no matter how much traffic you're getting Apache can do the heavy-lifting and MySQL only gets involved from time to time. Donncha's plugin suite brings sane caching to WordPress and helps make your site a lot more responsive
Subscribe to Comments Reloaded - while a lot of people seem to like offloading this kind of thing onto a 3rd party service I'm more comfortable running the comment subscriptions directly from my own server.
- Site Revamp (Sort Of) (michele.me)