I think I’ve managed to get WordPress rid of “category” (category_base) in permalinks.
It’s not a perfect solution, and it’s not like installing one plugin and clicking ‘activate’. But it will not take you more than 5 minutes to set it up, I promise
Browse around this very site to see what works and, possibly, what doesn’t. If you do find a link that leads you to a 404 error page, please e-mail me at: aesqe [at] skyphe [dot] org
Please download the Decategorizer plugin with all the necessary installation info from here: http://skyphe.org/code/wordpress/decategorizer/
You can post your comments there, as well.