Now that we have the simple abstracted cache, we may re think the entry cache.. I know we discussed just passing headers, but I was thinking how many request we can end up doing on a page:
1) the mwEmbedLoader.php/entry_id/ ... loader includes and entry_id check
2) the page calls the iframe .. loads entry again
3) the player includes a thumbnail on a change media call or what have you hits thumbnail.php and loads the entry again.
4) the page includes on-page chapters with 10 chapters, each hitting thumbnail.php all re-loading the entry each time

If we have clean access to the headers and can safely cache the entry, it may be worthwhile... but not very high priority.