Allowing other users to use blog?

I’m looking for a blog software that allows people to register and to post blogs within the same site. I tried a demo over at http://opensourcecms.com/ but I’m not sure if it was a limitation of their demo or a limitation of the software itself.
Basically, I want people to be able to register and then after verified, be allowed to post within a specific category on the site. I saw that wordpress has a registration system, but was unsure if this was only for comments or something more.
The main thing is that I don’t want these users to be able to access the admin control panel. Only be able to post blogs in a specific category.
If this isn’t available in the current build could it please be included in the next build? If somebody could reply and let me know if it’s already included and if not, if I could get an ETA on when I might be able to expect it that would be great.
Thanks!