Excellent re-invention of the 1999 Manila prior art. Now if this meme would spread to other blog systems!
At the fundamental level, EditThisPagePHP basically just let you remotely edit a single page. There are many situations where existing Wiki or Blog software is too complicated, or imposes too much structure. EditThisPagePHP lets you have total control over the HTML -- you can use sophisticated CSS layouts, or very simple HTML -- the software does not get in the way.
Yet in spite of this simplicity, EditThisPagePHP also uses ideas drawn from various Wiki, Blog, and CMS (content management system) technologies. Like Wikis, it supports an edit-this-page button, page history, page diffs, and can email users when pages change. Like Blogs, it supports optional user comments, trackbacks (both send and receive), and delivers two RSS feeds -- one for the current version of the page, and one with diffs. Like a CMS, it supports multiple roles, by default a reader, an editor, and a super-editor -- each with different privileges.