Yep! Its second in the line of lazy boy, or as Avatar calls 'em, slacker scripts! Grab the script at the userscripts.org entry.
The script effectively looks for posts which have the same words as the one in your title. It then displays those results to the right of your post editor. I am being a little sadistic and styling them to look like Google clippy ads ;) Hehe! You can ofcourse change the look by editing the inline styles in the userscript itself. Look for the addGlobalStyles function. Those familiar with CSS will find themselves in familiar territory!
A nice sideeffect to this script can also be to find posts to link to (which might be unrelated to the current one). A click on the post titles from the results will add them to Hybrid Link Field. Very useful when you have a lot of posts in your blog, and you need to make quick references to them.
Here is a screenshot of both my scripts at work on my post create page
If there are any conflicts with other userscripts or page scripts, please do let me know. Since Johan's post, I'd really like my scripts to work well in tandem with others.
Hope you find it useful! Enjoy!
[Update]: The links to change the values for Blogname and Results count have been made persistent, as asked by Effendi in the comments. More details on the userscript page! :)