WordPress 2.6.x introduced a new feature I’ll call version history. Every time you edit a post after it’s been published, the previous version is saved and a new ID is generated in the wp-posts table. So if you are a horrible speller or punctuationist (?) like me, every little ‘post-publish’ change you make results in a new table entry. The current core doesn’t seem to have any built in functionality to use version history (at least none that I can find) but it’s ripe for plugins or future releases to exploit. You can see all the revisions way down at the bottom of the write/edit post page. Just don’t prowl around the wp_posts table unless you’ve got a strong stomach. It’s a mess in there.