Russ Lavoy wrote:

I am in the process of migrating all our our mediawiki installations into one installation.

In order to do this I need to export all of the site data and re-import it into a category on a different site.

Is there any tool I can use to do this?

If not, what is the easiest way to accomplish this?

Thanks!

Export everything as xml and import. Adding category Foo to all pages from Bar is easy. You may have problems with page FooBar existing in different sites. Perhaps you should import on a different namespace depending on the source wiki (you'll still have problems with namespaces different than the main). Also, if the usernames of each wiki are different, you'll need to merge them...