Ok, I think this is it. Turning on logging gives this from tin:

 > var_dump( MessageCache::singleton()->load( 'it' ) );
 [memcached] get(itwiki:messages:it:hash)
 [memcached-serious] Memcached error for key "itwiki:messages:it:hash" on server "127.0.0.1:11212": CONNECTION FAILURE
 [memcached] get(itwiki:messages:it)
 [memcached-serious] Memcached error for key "itwiki:messages:it" on server "127.0.0.1:11212": SERVER HAS FAILED AND IS DISABLED UNTIL TIMED RETRY
 [memcached] add(itwiki:messages:it:status)
 [memcached-serious] Memcached error for key "itwiki:messages:it:status" on server "127.0.0.1:11212": SERVER HAS FAILED AND IS DISABLED UNTIL TIMED RETRY
 [memcached] get(itwiki:messages:it:status)
 [memcached-serious] Memcached error for key "itwiki:messages:it:status" on server "127.0.0.1:11212": SERVER HAS FAILED AND IS DISABLED UNTIL TIMED RETRY
 [memcached] add(itwiki:messages:it:lock)
 [memcached-serious] Memcached error for key "itwiki:messages:it:lock" on server "127.0.0.1:11212": SERVER HAS FAILED AND IS DISABLED UNTIL TIMED RETRY
 [memcached] set(itwiki:test)
 [memcached-serious] Memcached error for key "itwiki:test" on server "127.0.0.1:11212": SERVER HAS FAILED AND IS DISABLED UNTIL TIMED RETRY
 [memcached] delete(itwiki:messages:it:lock)
 [memcached-serious] Memcached error for key "itwiki:messages:it:lock" on server "127.0.0.1:11212": SERVER HAS FAILED AND IS DISABLED UNTIL TIMED RETRY
 [memcached] get(itwiki:messages:it)
 [memcached-serious] Memcached error for key "itwiki:messages:it" on server "127.0.0.1:11212": SERVER HAS FAILED AND IS DISABLED UNTIL TIMED RETRY
 [memcached] add(itwiki:messages:it:status)
 [memcached-serious] Memcached error for key "itwiki:messages:it:status" on server "127.0.0.1:11212": SERVER HAS FAILED AND IS DISABLED UNTIL TIMED RETRY
 MessageCache::load: Loading it... global cache is empty, waited for other thread to complete, global cache is empty, could not acquire status key., loading FAILED - cache is disabled
 bool(false)

I think at this point we need to get an ops person involved.