All items from the hopper end up in the left chest.
The same thing happens when the two chests are underneath. The hopper sends any items in it to the normal chest next to the trapped chest that's actually beneath the hopper. EDIT: For whatever reason, this site isn't letting me upload additional screenshots so I'll just leave this http://i.imgur.com/zwjHU.png here. Someone else can upload it correctly if they can. This image is a configuration that doesn't work. Any item placed in the hopper ends up in the left chest.
I would say that because the redstone block is in the shape of a solid block, it should behave like a solid block. It doesn't really make sense how it is IMHO.