We already reported about a few of the new pets to be found, including a cool purple tallstrider, but there's at least one more out there called the Skettis Kaliri, probably found in the Arrakoa capital, a new quest area. In addition, there's those two new pet skills, Avoidance (which should help with DPS pets in raids and instances), and Cobra Reflexes, which increases attack speed at the cost of damage per attack. In tests, Petopia says it does increase DPS overall, but it remains to be seen how it will work on the live realms. Both skills should be trainable at the pet trainer (although that may be only for the test realm, again not sure).
If you're a hunter (or just want to know what you might be facing in the high level battlegrounds-- I would hate to get beat up by a purple dodo), Petopia's page is definitely worth a look before the patch drops as a great overall view of what's happening in petland.