plug-in to allow specific users to edit specific pages/posts

I am looking for plug-in that I can manage users with and allow them to have editing access only to specific pages/posts on the site.

I know I can set up users to only post to their blog rolls and what not, but I am looking for something that will allow them to only have access to specified areas of the site.

I’ve been searching but can’t find a plug-in that does something like this.

Basically we are running a site that each employee has their own page and/or blog. we want them to be able to log in and have easy access to the areas that their user account and/or group can edit.