The head of the Catholic Church, Pope Benedict XVI, has signed up for Twitter with the handle @pontifex (latin for "bridge builder," meaning pope). He'll send his first tweet from the account on December 12th to coincide with the festival of Our Lady of Guadalupe. Tweets from @pontifex will be in English, but will be mirrored via separate accounts in Spanish, Italian, Portuguese, German, Polish, Arabic, and French.
Through the official announcement, the pope is inviting questions to all the above accounts, which presumably he'll do his best to answer after his initial tweet. Although subsequent postings are likely to be handled by his advisors, the first tweet from @pontiflex will be sent by the pope himself. Benedict XVI isn't totally new to Twitter, however: last year, he sent a tweet through the Vatican News account, inviting users to check out the out the site.
There are already a number of fake Benedict XVI accounts on Twitter, including @BenedictusPPXVI, and Vatican officials told Sky News they "hope that all fake Pope accounts will stop once the official account has launched." Good luck with that.