In case you missed it, today’s New York Times includes a full page ad from the Freedom From Religion Foundation.
It explains how the National Day of Prayer is unconstitutional (click image for PDF):

Talk about an advertising blitz. This ad plus the bus ads which go up in Madison today will no doubt generate a lot of discussion.
Hopefully, the government’s appeal to the National Day of Prayer case will fall flat… it’s not likely, but the constitution is on FFRF’s side.