Just released: A very simple plugin that allows you to require SSL for certain pages on your site. For example, at the BDN we moved the login form from /wp-login.php to /login/, and wanted to require SSL for that page. So, using this plugin, we can force anyone who visits http://bangordailynews.com/login/ to https://bangordailynews.com/login/.
It’s in the WordPress plugin repository: http://wordpress.org/extend/plugins/require-ssl-for-pages/
Is there a particular reason you did it inside WordPress rather then on a server configuration level?
Mainly because it’s easier to manage this way.