Those Doomsayers in Orgrimmar have at least now got another purpose other than giving you pamphlets for an achievement - now there is the chance that one of them will be a Dread Infiltrator and give you the chance of getting the Pocket Fel Spreader toy.
So what do you have to do?
You have to have the ability to be able to see demons - like a Demon Hunter with spectral sight, a hunter with track Demons, wearing the Cursed Vision of Sargeras (which is the blindfodl that drops from Illidan in Black Temple) or using the Elixir of Detect Demon - then you will be able to see the extra speech option when you talk to a Doomsayer.
You need a few people to kill the Dread Infiltrator - you don't want to die if you're the only one who tagged it or it will despawn.
It hits like a truck! And it can mind control you, put you to sleep... all manner of annoying things. The first time we killed it was a few mins before reset, when HK found one near Orgrimmar's main gate, and then the second time Sev found one in Valley of Hono(u)r. Since then I've joined PuG groups in group finder as there are a lot going around, but I've seen a few on Saurfang too. Kyxyn has a fantastic 100% drop rate (2/2), and I have been trying to get more to give to guildies, having had 2 drop myself.
Good luck to you when you're farming it! I have noticed today that times to spawn can be very variable in those PuG groups, but on Saurfang I feel like I see it at least once every hour.