I do for one. It's too bad I'm a Groovy/Java/JavaScript guy and not a Ruby guy, or I'd offer to give you a hand. Are you thinking that, since you already have the new API code in the rewrite, you could just transplant it to the current codebase?
As you've pointed out, we always have the .markdown files. I've got something set up using MDwiki on Amazon S3 that I can transfer my pages to, but WikiPack is nicer since it has an integrated editor.
Whatever you decide, thanks for developing WikiPack and hosting it for so many years. It's been really useful to me.