It seems to be active but it’s difficult to tell.
A Gibbering Gemstone is needed to craft a Staff of Herding which is used to unlock Whimyshire (the secret cow level of Diablo 3). Beyond, you will find rainbow colored ponies and other cute creations from Blizzard. The whole process requires you to collect 5 rare or expensive items, a rare recipe (the Plans: Staff of Herding) and then spend 50,000 gold to combine them. Once you have your staff you can unlock Whimshire whenever you want.
Where to Find Gibbering Gemstone
The Gibbering Gemstone is the hardest of the reagent to obtain, so I suggest you find it first instead of last. There are three parts to this, 1) find the cave of frost (or Icefall Caves). 2) find Chiltara and 3) kill and hope that Chiltara drops the Gibbering Gemstone.
Finding the Cavern of Frost / Icefall Cave
Create a game at Act III – Machines of War. Run through the gates and across the bridge until you’re in The Fields of Slaughter. Later you can use the way point to The Bridge of Korsikk to get closer. Check the following 6 known spawn locations of the cave:
Once you’re in the caves just run through, both levels, looking for Chiltara. It’s a purple rare and doesn’t necessarily share a spawn point with anything else. Search the entire cave, every time, until you find it. If you’re playing on a low difficulty watch carefully that you don’t 1-shot him and miss the fact that you could recreate the game. If you clear the entire cave them teleport, leave and resume to restart the game.
It drops off Chiltara. If it doesn’t drop, you get to start over. Good luck!
Warning: This item can take a really really long time to find. Some of the other items require a similar amount of time.