Lightroom Catalogs: One or Many?

Interesting discussion on John Beardsworth's blog. It seems to be in reaction to the O'reilly blog which suggests  a rather cumbersome (to me anyway) method of using multiple catalogs for different subject types.

As John points out, the only two reasons they seem to have are:

1. Its a work around for catalog performance problems that might be experienced, and
2. They are using Lightroom more as Adobe Bridge rather than a true database.

As you may be able to tell, I'm on John's side. Especially as you're bound to end up with shots that fall into several catalog categories you've set up. What do you do then? Add it to all relevant catalogs? This seems a little messy to me.

You can read John's full article here.