This is, as Alex Koppleman points out, John McCain's last shot at a TV audience anywhere near this large before Election Day. For Barack Obama, not so much.
Obama's campaign has bought 30 minutes on major broadcast networks on Oct. 29, to air at 8 p.m. Earlier today, Obama aides finished negotiations with Fox, which agreed to delay the start of Game 6 of the World Series (if needed) so the campaign infomercial could air. (Republicans are already grousing that this means Obama not only doesn't put country first -- like they say McCain does -- but doesn't even put baseball first.)
The buy means Obama will have another shot to address huge numbers of voters as they sit on their couches, just days before they vote. McCain, meanwhile, will have to hope tonight does the trick.