state of the wiki
Hmm... I don't think there is a way to merge pages that preserves history for both. I suspect the best option would be... move the page with the most history/content to the new name (if it's not already the correct name), and add the content and discussion-history from the other page.
One thing that could maybe be done is have the "edit summary" include a link to the history of the other page. That way a link to the other appropriate history is there when people are viewing the page history.