Historically, there were some rock groups that put satanic messages into some of their songs, which could be heard only when they were played backwards. Last night there was a caller on C2C AM radio show, who said that he played some of Obama's last year's speeches, and when it got to the "Yes we can" part, it sounded like "Thank you satan", when played backwards.
Now that doesn't really prove anything, but it's very interesting that Obama's MAIN slogan, 'yes we can' would sound backwards when he said it, as thank you satan. There's also some theory that by playing people's speech backwards, it will reveal what they really mean. You may wanna google 'reverse speech' for more info.