Nice simple plugin, but comes with a huge flaw. It sets default category even for new Pages, which can cause bad issues. Normally you wouldn't notice that, since Pages edit form doesn't show 'Categories' edit box. For example, if you have a member only area and you block posts in default category, your new added pages will be blocked too. You can show 'Categories' box in Pages edit form with "Add Categories to Pages" plugin and see it yourself. Plugin author: Make a select box in a plugin settings panel so user can choose which post types it will affect, or place a warning message to the plugin description please.