Season 4 came to an end last week, with existing arena teams and ratings wiped during the extended maintenance earlier this week. Arena points will persist on a character until he or she hits level 71, allowing them a chance to spend any that remain. Arena Season 5 will begin on December 16th, giving everyone a chance to level to 80 and enjoy all the next content in Wrath of the Lich King.
Until that time, players can still participate in Arena skirmish matches in two new brackets (71-75, 76-80) if they want to hone their skills prior to the new season. After the 16th of December and the new season, normal Arena rules will be restored and players will be able to compete for gear and end-of-season rewards.