Jim Fulton writes:

In theory, you could use ZCatalog to catalog objects in the file system or in a RDBMS, providing that you can provide paths for them. I don't think anyone's done this yet. There are bound to be bumps from wjoever does it first. :) I use ZCatalog to catalog objects in the file system included into the Zope world via LocalFS. Minor patch to LocalFS needed. Everything works with the exception of proximity searches.

Dieter