WordPress.org

Single Post Message is a plugin that allows you to add custom messages, announcements, and notices to individual posts. It's styled to grab the reader's attention and will render in both the browser and in RSS readers.

Single Post Message...

• Supports the use of HTML tags in the message content
• Provides a live preview for what your announcement will look like
• Is available directly under the post content editor
• Is fully localized and ready for translation

For more information or to follow the project, check out the project page.