http://www.worldofraids.com/forum/viewtopic.php?t=1538
Some pretty nice screenshots with loot and encounters that can be found in Karazhan, along with a link for a video for the last encounter in it.
A part of it seems to be the Opera House, with acts as 10-man encounters with bosses.
I wonder if Little Red Riding Hood or Snowhite would make a nice opera... Dont ask and just check it. 
http://www.worldofraids.com/forum/viewtopic.php?t=1501
Could this finally be that less than 40 man, or even 25 man groups will be able to get some action? Let's wait and see.