Based on this, it seems like it did http://blockchain.info/p2sh but it seems I can't find a definitive answer.
2 Answers
Yes it did, on April 1, 2012.
[removed link to chain of orphaned blocks]
Yes, it did.
BIP: 16
Title: Pay to Script Hash
Author: Gavin Andresen <[email protected]>
Status: Final
Type: Standards Track
Created: 2012-01-03
(Final is the stage after being accepted - it means that it's done.)