I just uploaded the source code and added a Confluence page for a Wiki Importer. We’ve had a rough JSPWiki importer for a while, but this is an improved version that also supports TWiki, courtesy of one our generous users.
It may still be a little rough, but it should be enough to get started with. If you have any problems or find anything that needs improvement, let us know.
Hopefully, this code can serve as framework for developers who are working on exporters from other wikis. In particular, we’ve had some folks asking recently about DocuWiki and MediaWiki. If you’re working on such a project, take a look. And if you would like to make any improvements, drop us a line and we’ll grant you subversion access to do so.

Confluence Wiki Importer Tool