Zul'Gurub is gone as a raid instance come Cataclysm. ~Valnoth
It was confirmed this week. Over 18 months ago I wrote a post on farming ZG for the mounts and mage book. The only change I would make is add a fourth goal...the pet
4. Razzashi Hatchling
This pet sells for a lot of gold. But beyond that with the removal of the raid the mobs that drop this pet will vanish.
In the area of Bloodlord Mandokir are 3 packs of 6 Razzashi Raptors . Then just outside his area is a smattering of the raptors with trolls.
If you are there for the mounts I would highly recommend killing the raptors too. If you want to farm the pet *shiver* go to the raptors and kill them and reset the instance as many times as you want.
Me? I might just pay a fortune on the Auction House to pick myself up one. Or at least keep my eye out for one to resell after Cataclysm.