Hi, this is a very very useful plugin, it's a shame it's not being updated for WP 3+.
However, this patch here: http://wordpress.org/support/topic/plugin-wp-crontrol-making-it-work-in-wordpress-27?replies=1 works!
The only problem I noticed it this PHP Notice: Use of undefined constant __ngettext_noop - assumed '__ngettext_noop' in /public_html/wp-content/plugins/wp-crontrol/wp-crontrol.php on line 647.
If ever you think of updating the plugin, or anyone resumes its development, please fix this one too.
PS: I would be glad to do it if I knew how..