A federal judge has rejected an attempt by atheists to prevent Barack Obama from swearing to "preserve, protect and defend the Constitution of the United States, so help me God." The plaintiffs, led by Michael Newdow, who unsuccessfully asked the Supreme Court to remove "under God" from the Pledge of Allegiance, should have realized that, legally speaking, they didn't have a prayer.
Newdow targeted two features of the inauguration ceremony: Chief Justice John G. Roberts Jr. would be prompting Obama to swear "so help me God" (even though the phrase isn't in the Constitution) and clergy members would offer prayers. But Obama has a 1st Amendment right to give voice to his religious beliefs, and the invocation and benediction are comparable to the prayers by legislative chaplains that the Supreme Court has upheld as "deeply embedded in the history and tradition of this country."
Still, you don't have to be a crank to wonder why it's an unconstitutional establishment of religion for prayers to be said in public schools -- and even at school football games -- but not at an inauguration. One answer is that children are a captive audience and susceptible to proselytizing to which adults are immune. That common-sense distinction has proved useful to the courts in balancing government neutrality toward religion with the fact that, as the late Justice William O. Douglas put it, "We are a religious people whose institutions presuppose a Supreme Being."