I recently installed [V.J. Catkick@’s Twitter Plugin for WordPress][1]. Shortly thereafter I noticed my [HTML validator Firefox Plugin][2] changing from a pleasing green check mark to a nasty red cross complaining about (X)HTML validation errors.
[1]: http://www.vjcatkick.com/?page_id=5475
[2]: https://addons.mozilla.org/en-US/firefox/addon/html-validator/
So I took the liberty of fixing the plugin’s generated code to produce valid XHTML.
The patch can be downloaded [here](http://perfect-co.de/wp-content/uploads/tw_vjck.patch).