I'm sure I'm not the only one that would welcome this addition to WP.
I have web sites running WP, which is being used as a central gathering spot for different stores in a shopping center.
I would LOVE to be able to allow each store owner the ability to edit their own PAGE. I don't want them to be able to add or edit links, or anything, other than the PAGE they own.
As it stands, giving a user the capability to edit a PAGE also gives them power to mess with links and all sorts of other stuff I can't trust them with.
You can assign capabilities to lower level users to write and edit POSTS, but not pages, and not allow them to mess with anything else. Even assigning the ONLY ability to edit their own PAGE would rock. No writing, just editing what I give them to edit.
I tried with one group by assigning higher levels, but people started tinkering with things that made a huge mess.
I LOVE WP, I've got WP running over a dozen sites I run now, for myself and for clients, and it just keeps getting better and better.
I'd love to see this as an addition to WP.