Which song plays in episode 56 at 11:32
I'm pretty sure this sound track does not actually have a name. You can find it by googling ~ BLEACH OST - Shiro Sagisu - BL_86.  I think BL_86 was the official title of this sound track.

Youtube video with soundtrack

Edit: Upon further diggin. BL_86 is the offical title of this soundtrack. It appears in Bleach 5th Anniversary Box CD 1.