The World of Warcraft Website announces Blizzard has opened registration for the 2012 World of Warcraft Arena Pass for the MMORPG. You can register here for USD $20.00 per account. The Frequently Asked Questions has more details on this, and here's word:

Participants will be fighting their way through the ladder ranks, testing their mettle against the best Arena players in World of Warcraft. Players that register for the Arena Pass will also be eligible to earn Murkimus, the Armored Murloc in-game pet, as a reward for participating. The top 1000 teams will also earn the exclusive "Vanquisher”" title for their live characters, proclaiming their puissant skill in battle for all the realm to see.

Don't forget, players that participate in this year's World of Warcraft Arena Pass will also gain exclusive access to a level-90 Arena Pass realm after the account is upgraded to the Mists of Pandaria expansion.