I'm pretty sure you can't edit the blog number, but you can edit everything else to (effectively) swap blogs around. The thing is your categories are attached to a blog number, so if you had a category called "dogs" in your "pets" blog and a category called "redheads" in your "girlfriends" blog you could easily end up with "dogs" in your "girlfriends" blog and "redheads" in your "pets" blog.

You would then have to go into your conf/_admin.php file and change $allow_cross_posting to 3 - which lets you move cats from one blog to another. I used to think, and I could be wrong, that you also had to change $allow_moving_chapters in the same file to true. If you change it and don't need to it won't hurt, and you'll probably change both these values back after you shuffle your blogs, so I'd just change it.

That sounds like it might not work then. I do have the "allow crossposts" enabled but I'll have to take a look at the "moving chapters" thing and see if that would allow me to recover easily if I destroyed all the order - what little I actually have... :) Thanks once again for the help and ideas!

Sometimes it can be possible
But be very carefull!
BEcause you have to do it in phpmyadmin.

Like EdB said, categories are attached to blogs.
So.. if you swap the numbers of blogs in phpmyadmin, you also have to swap the numbers of the belonging categories.

I did this once in a 0.9.x version, at was no problem.
But I also did it in a 1.8 version, and I had to restore my database 2 times..
There is a thing with the plugginns and the files attached to blogs.. but I'm not shure what the thing is..

At the end I managed to swap 2 blogs, but it took me 2 days (in version 1.8)..

SO : NEVER DO THIS WITHOUT MAKING A BACKUP FIRST

Cautions are enough to deter me as I'm very new at this whole thing. I'll be looking for another, safer way to accomplish this. Thanks for the info!