I realize the best answer to this problem is to make sure writers are choosing a category. Unfortunately, in my installation I'm dealing with several hundred people and there  is just no way to enforce this.  I don't have a problem if posts get assigned to the default category, I can filter for this and fix them as they appear. However, I have many posts being saved with no category at all these are harder to find amongst the hundreds of new posts created each week.

Is there any way to enforce the selection of the default category if the proper category is not selected? It seems that WP should be doing this by default and it could be a problem with my installation since I know that I have problems with my category structure at the db level.

it seems that the category problem is corrected in the newest dev snapshop. Even better, for a user with a single category allowed the post saved to that category even when none was selected.

Thanks!