One of the fruits of this effort was a jQuery plugin called MessageBar. Here's what it looks like when it shows up on Django Packages:
|jQuery MessageBar, as seen at the top of Django Packages
Consider this a gift to the front-end developer community. It is free and open-source, available on GitHub: https://github.com/audreyr/messagebar
It works particularly nicely with Django's messages framework, but Django isn't required. It's just HTML, CSS, and JS. Therefore, it would work just fine with any PHP or Ruby site, for example.