I see that at the majority of WordPress blogs the owner is his own mod. But there are some sites which reached a size that made it necessary to 'outsource' the job. And WordPress 2.0 actually supports bigger sites with the 'roles' feature, which specifically enables the owner to assign users for special tasks and give them the capabilities to help in managing the blog. But what's missing is a report functionality that monitors the actions of those users and allows the owner to establish some oversight.
Since WordPress is based on MySQL, it shouldn't be too difficult to add additional fields for the database, for instance a 'delete' flag, an entry for date and time of deletion, and a cross reference to the user who executed the action. This would make it possible to generate reports on the deletions of every registered user, giving the owner the chance to evaluate if the mod power is used in his best interests and asccording his guidelines. I haven't done database programming since several years, so I might be wrong, but for me it seems this wouldn't be too complicated to implement. And it sure would be a useful tool supplementing the role features of WQordpress 2.0.