Yes, this is something that we have toyed with the idea of implementing. However, for now we have decided to contact posters individually and on a case by case basis if we see this happening, as the problem we thought we might encounter was that if someone has posted a story and then sees some breaking news, we want them to be able to post that, and not be restricted by the site.

We could look into something that kicked in when stories got up to say, more than five an hour, but for now we are looking at this issue manually. If you see this happening, please feel free to contact me and let me know.