This plugin lock the edition possibility of a post after 12pm.
With this plugin active, it's impossible to edit posts that have a day of creation witch is not today.
In brief, the edition possibility is desactivated after 12pm, even if you are the author.
An exception is added since version 0.3 : if a posts are stickies, the edition is possible until the stickies tags are unchecked. This work with the standard sticky feature of wordpress and with WP-Sticky plugin.
Only the administrator still have the possibility of edition.