This is the most common support email we get, so I think it's worth mentioning on the blog. If you need to change your username & URL then you can now do so directly on the account settings page:
We'll automatically set up a redirect for you, any old links you have floating around will still work. This works for purchases and download keys you've distributed as well.
In order to keep changing usernames at a reasonable level, you must wait 1 week after changing your username before you can do it again. Make sure you think it through before you hit save. If, for whatever reason, this limit is preventing you from doing something you need feel free to send us an email.
(and special thanks to Gran PC his first feature launch)