I've just installed the latest beta of Wordpress (multisite), Buddypress 1.5.1, and Wiki. The Wiki plugin appeared to install without an issue. I was able to add, publish, and view a Wiki page.
However, when I navigated to the site dashboard Appearance>Menus, the box where I should see my Wiki(& sub-wikis) was not visible, so I could not add it to the menu. Is there some step that I missed?
The next issue: when I viewed the published wiki page, I could see all of the tabs but when I clicked on either the "Edit" or "Create new" tabs, all of the tabs and breadcrumbs disappeared leaving only the Wiki title. AND it took away the Wordpress Admin bar. Just thought you should know...