David Liontooth wrote:
The effect was a messed up cache function -- the second wiki's Main_Page would consistently display in the first wiki. If I selected [Edit] and Preview, I would see the first wiki's real Main_Page intact, but saving it would revert the display to the second wiki's front page.
This is probably because you were using a table prefix to distinguish the two wikis, rather than a different database. This is not supported properly by MediaWiki, and will be a problem whether you use Turck or Memcached. The DB-based cache is the only one that's immune, since it's stored in a table with a prefixed name.
-- Tim Starling