I've just been messing with my apache, and recompiled everything, and now FB doesn't work.
Line 1023 of lib/FB/User.pm is the first failure point...
at my $db = @FB::MEMCACHE_SERVERS ? FB::get_db_writer() : FB::get_db_reader();
Now i havn't changed any of my FB settings, and I only have a master setup, so any ideas?