Yes, but it is very slim (about 1-2mm).
Here is the post I was referring to: (post #14):
http://forums.pimoroni.com/t/unicorn-hat/28/
Judging by the 3rd picture here, I can’t see it fitting:
http://makersify.com/blogs/adafruit-blog/16056941-new-product-pimoroni-unicorn-hat-8x8-rgb-led-shield-for-raspberry-pi-a-b
Mine looks exactly this one on the top left:
http://makersify.com/blogs/adafruit-blog/15241617-new-products-ninja-pibow-timber-pibow-pibow-coupe-rainbow-pibow-enclosures-for-raspberry-pi-model-b
There’s also this quote from Rapid Online:
The Pibow Coupe cases are ideal, the Pibow Ninja, Rainbow and Timber cases won’t do unfortunately. Whilst the Unicorn sits neatly on the B+, it won’t do that with the B but it’s possible to hack it to work, letting B owners enjoy the blinkiness.