I just wrote a plugin that does effectively the same but actually deletes the Recent Changes entry from the database. On trying to create a page for it (with the exact same title as your plugin) I found out about this plugin... Your solution is so much cleaner I'll just abandon mine. Thanks for the plugin!
Topic on Extension talk:Recent Changes Cleanup
Appearance
Yea, with this one if you need to see which ones have been hidden, you can do "show bots".