Lots of news reports on this, including the Chicago Tribune. WorldNetDaily has an article:
The so-called war on Christmas has been reignited with an ironic decision by the city of Chicago to ban advertisements for "The Nativity Story" movie from a local Christmas festival, fearing they might offend non-Christians.
"This is one of the most blatant forms of religious discrimination imaginable," said Jay Sekulow, a Christian who is chief counsel of the American Center for Law and Justice. "To suggest that a movie about the birth of Jesus Christ should not be included in a Christmas festival is absurd.