enable network/matrix expiration, this should be functional but the options have been reduced/restricted so we're only looking at network posts and ignore anything that is filed, starred, or is resource_type 'photo' (which should not be possible in non-wall posts, but we just want to be sure). Will require the adventurous tester(s) to set 'channel_expire_days' in their channel record.

boot.php

@@ -528,6 +528,8 @@ define ( 'ITEM_MENTIONSME',      0x0400);
 define ( 'ITEM_NOCOMMENT',       0x0800);  // commenting/followups are disabled
 define ( 'ITEM_OBSCURED',        0x1000);  // bit-mangled to protect from casual browsing by site admin
 define ( 'ITEM_VERIFIED',        0x2000);  // Signature verification was successful
+define ( 'ITEM_RETAINED',        0x4000);  // We looked at this item once to decide whether or not to expire it, and decided not to. 
+										   // Don't make us evaluate this same item again. 
 /**
  *
  * Reverse the effect of magic_quotes_gpc if it is enabled.