HDL

New Pets
Spring Rabbit - Right Click to summon and dismiss your Spring Rabbit.
Plump Turkey - Right Click to summon and dismiss your Plump Turkey.
Teldrassil Sproutling - Right Click to summon and dismiss your Teldrassil Sproutling.
Tirisfal Batling - Right Click to summon and dismiss your Tirisfal batling.
Dun Morogh Cub - Right Click to summon and dismiss your Dun Morogh Cub.
Durotar Scorpion - Right Click to summon and dismiss your Durotar scorpion.
Alarming Clockbot - Right Click to summon and dismiss your Alarming Clockbot.
Elwynn Lamb - Right Click to summon and dismiss your Elwynn lamb.
Mulgore Hatchling - Right Click to summon and dismiss your Mulgore hatchling.
Ammen Vale Lashling - Right Click to summon and dismiss your Ammen Vale lashling.
Strand Crawler - Right Click to summon and dismiss your Darkspear Strand crawler.
Enchanted Broom - Right Click to summon and dismiss your enchanted broom.
Argent Squire - Right Click to summon and dismiss your Argent Crusade squire.
Mechanopeep - Right Click to summon and dismiss your Mechanopeep.
Argent Gruntling - Right Click to summon and dismiss your Argent Crusade gruntling.
Curious Gorloc Hatchling - Right Click to call or shoo away a Curious Gorloc Hatchling.
Curious Wolvar Pup - Right Click to call or shoo away a Curious Wolvar Pup.
Gorloc Orphan - Right Click to summon and dismiss the orphan you've agreed to look after for Children's Week.
Wolvar Orphan - Right Click to summon and dismiss the orphan you've agreed to look after for Children's Week.
Murkimus the Gladiator - Right Click to summon and dismiss Murkimus the Gladiator.
Sen'jin Fetish - Right Click to summon and dismiss your Sen'jin fetish.

New Mounts
Aquatic Riding Ray - Summons and dismisses an Aquatic Riding Ray. This is an aquatic mount.
Swift Stormwind Steed - Summons and dismisses a rideable Swift Stormwind Steed. This is a very fast mount.
Great Azuremyst Elekk - Summons and dismisses a rideable Great Azuremyst Elekk. This is a very fast mount.
Swift Darnassian Mistsaber - Summons and dismisses a rideable Swift Darnassian Mistaber. This is a very fast mount.
Swift Silvermoon Hawkstrider - Summons and dismisses a rideable Swift Silvermoon Hawkstrider. This is a very fast mount.
Great Mulgore Kodo - Summons and dismisses a rideable Great Mulgore Kodo. This is a very fast mount.
Turbostrider - Summons and dismisses a rideable Turbostrider. This is a very fast mount.
Swift Ironforge Ram - Summons and dismisses a rideable Swift Ironforge Ram. This is a very fast mount.
Swift Sen'jin Raptor - Summons and dismisses a rideable Swift Sen'jin Raptor. This is a very fast mount.
Forsaken Warhorse - Summons and dismisses a rideable Forsaken Warhorse. This is a very fast mount.
Swift Orgrimmar Wolf - Summons and dismisses a rideable Swift Orgrimmar Wolf. This is a very fast mount.
Mimiron's Head - Summons and dismisses a rideable mechanical gnome head. This is a very fast construction. This construction can only be summoned in Outland or Northrend.

Have to collect them all  :P

Wait...a ridable gnome head (http://static.mmo-champion.com/mmoc/images/news/2009/february/mimiron_headmount.jpg)?? ROFLMAO

Hmm, I also see from that list that we'll possibly be getting new Children's Week quests from The Oracles or Frenzyheart Tribe in Sholazar Basin.

I'm guessing that these new pets and mounts are from the Argent Tournament?
http://forums.worldofwarcraft.com/thread.html?topicId=15198917105&sid=1

QuoteIn patch 3.1, a new world event titled "The Argent Tournament" will be coming to Northrend! This tournament will be live on the 3.1 PTR and open for testing, though certain aspects are still in development. Players will find a host of new features here, including:

The ability to prove your worth to a capital city of your choosing through our new mounted combat system (still in development)

New daily quests to construct the great Argent Crusade coliseum for glorious battles to come

All new rewards - new items, titles, banners, tabards, pets, mounts, and more

All new achievements

Many more festivities, and more to come in future content updates!

Players will find the Argent Tournament in Icecrown. Speaking to any Northrend flight master will get you on track to prove your worth to the Argent Crusade, your faction's leaders, and all denizens of Azeroth!