If you place a row of hoppers in a loop, as shown on the attached picture, and place a second set of hoppers beneath the loop to take items from it, you'd think the items put into the loop will get distributed amongst all hoppers of the bottom layer evenly.

However this is not the case. It seems that no matter how many hoppers you use for the loop, when you place a stack of 64 items in the loop, it will only split up into two stacks of 32 in the two bottom hoppers closest to it.

It seems that the bottom layer is preventing the items to make the loop in the top layer of hoppers. In a perfect world, this wouldn't happen.

Note: If this would work the way I said in the first line, it would be very useful for automatic smelting machines which use multiple furnaces at once.

Edit:
Bonus: I think this problem is related: http://imgur.com/qlqiwNz
What you see here is a single item sorter module with a similar hopperloop above it. This set-up doesn't work (even though it should). When you place an item in the loop at the top, it will only get sorted if you place it in the hopper closest to the item sorter thingy, if you place it in any other hopper in the loop, it will not get sucked down and just stay looping.

Edit 2: Whoops, seems like someone already reported something similar. My mistake.