You've got until November 11th to switch over to battle.net or else your account will be disabled until you do. It's quick and simple and we've got an awesome guide on our forums to do it.

A few months ago, we unveiled the Battle.net account, our new way for players to log in to World of Warcraft and future Blizzard games, sign up for upcoming beta tests, shop the online Blizzard Store, and more with just one username and password. This was just the first step in the rollout of the brand-new Battle.net; in the future, players will be able to use Battle.net to participate in cross-realm chat in World of Warcraft, create real-life friends lists, communicate across different games, and a whole lot more.

In preparation for the launch of these new features, on November 11, 2009, all current World of Warcraft players will be required to merge their World of Warcraft accounts with a Battle.net account in order to log in to the game. As our way to say “thanks” for taking a moment to go through the process, existing World of Warcraft accounts that upgrade to Battle.net (including those that have already switched over) will receive a brand-new penguin in-game pet -- check for him in your in-game mailbox later this week. Starting on November 11, all World of Warcraft players will need to log in to the game using a Battle.net username and password, and anyone who wishes to create a new World of Warcraft account will need to start with a Battle.net account.

Here's the blue post and here's our forum post on it that has some awesome details on how to do it.