How do you change a post title with an action or filter?

One example here at the bottom:

https://comox.textdrive.com/pipermail/wp-hackers/2008-January`/017099.html

function foo_the_title( $title ) {
    if ( 'About' == $title ) {
        return 'New Title';
    }
    return $title;
}
add_filter('the_title', 'foo_the_title');