Yesterday's snapshot has been fixed for a second time (the first time gave the previous link).
Originally Posted by http://mojang.com/2012/02/03/minecraft-snapshot-12w05b/
We decided to do an extra update of the snapshot this week. The reason was because of the shift-click bug when crafting items, which would consume all the items in the crafting table and only produce a single result item. This bug is troublesome because it’s such a fundamental feature, and we don’t want to penalize people if they forget that it’s broken.
We also fixed so that cats can be told to sit with an empty hand.
Get the snapshot here: