Does Wiki have an importer?

I'm wanting to seduce a popular blogger onto my multisite network who runs a very extensive Wiki for my niche using MediaWiki. I have no idea how that program works, but does the wiki plugin have an importer? I'd love to host the guy's blog and integrate his Wiki into it using the Wiki plugin, but I don't even know if it is possible as a replacement to another product. He is committed to his Wiki, so he may not leave MediaWIki behind unless I can make it really easy for him.

Is it even possible? Should this be a feature request? (yes, if it isn't already possible!)