I've been using the plugin for years, and I am just encountering an issue with any blogs I've updated to WP3.
I have the plugin set to show on both the site and the admin area. However, when I click Appearance > Editor from the site, I get the following error message:
Cannot load theme-editor.php.
This doesn't happen when I do the same in the admin area.
All things are the same as they have been for ages, with the exception of the upgrade to WP3.