Minecraft 1.4.1 Release; Developer Nathan "Dinnerbone" Adams described the bug that was causing mobs to suffocate and fall through wooden floors

Minecraft PC release pushed back slightly as 1.4.1 pre-release patch is sent out Examiner.com
The new release date for the Minecraft 1.4 update was pushed from Wednesday to Thursday, October 25. Developer Nathan "Dinnerbone" Adams described the bug that was causing mobs to suffocate and fall through wooden floors a "doozy" on Twitter.

Minecraft 1.4.1 Provides An Extreme Amount Of Fixes The Droid Guy
This upcoming patch to Minecraft is due to hit players clients on this Thursday, October the 25th.