Okay, I had a look at the WordPress we have running on the site today, and discovered that users of the same level cannot edit each other's posts. Personally, I think it would be good if they could because then we could all help each other in terms of spell checks, tweaks, etc -- which would hopefully result in higher quality posts.
Apparently, according to those in the know about such things, prior to WordPress 1.5, people were complaining because people with the same user level *could* edit each other's posts, so they changed it like it is now. However, I am also told that a plugin could be written to change this behaviour back. Before plunging in and trying to do so, I thought I'd better check that such behaviour is desirable. If so, I'd only make it possible for the devs, who have had their user level raised, because we wouldn't want people submitting drafts that can be edited by anyone with an account.
On this note, I'd just like to explain one thing: I chose a user level of 5 for developers because if you go any higher, you start getting into configuration options and stuff -- I didn't want to over-complicate things, and I'm really the only person who needs to worry about configuration. For a full explanation of what the different user levels do, have a look here: http://codex.wordpress.org/User_Levels. If anyone objects to my decision of the default developer user level, do feel free to say so.
Jon