With ugly URL's, a link such as
will work just fine.
However, once "pretty" URL's (permalinks) are enabled, author pages don't work at all (I'm using twentyten theme). This URL should (but won't) work:
Give it a try and you'll see that the ugly URL will redirect you to the nice URL but it won't work.
It returns twentyten's default "Not Found" page. Anyone have this problem or know how to fix it?