Rappers want to be athletes and athletes want to be rappers. Singers want to be actors and actors want to be singers. Entertainers long to be taken as seriously as politicians and, as far back as the days when JFK was hanging out with Frank Sinatra and sneaking around with Marilyn Monroe, politicians long to be as cool as entertainers. The world of celebrity (or maybe just the world, in general) is all about the grass being greener on the other side.

Nowhere is that more evident than at the Democratic National Convention, where stalwart political types hobnob ecstatically with A-List stars who are equally as ecstatic to shake hands with people less famous but ultimately more important than they are. Spike Lee, Pharrell Williams, Angela Bassett, John Legend, Danny Glover, Ben Affleck, Susan Sarandon, Kanye West, and many others have flocked to Denver to celebrate with the ultimate A-lister of the moment, Barack Obama. Not only do Hollywood celebs bring other non-traditional media to these events — Access Hollywood, Entertainment Tonight, Us Weekly — they add a coolness factor, which, while off-putting to some voters, is surely impressive to others.

In the end, though, it's really just about one kind of celebrity mixing with a different kind of celebrity. That's where John McCain's celebrity ad was so off base. Besides the preposterous Paris and Britney comparison, the most ridiculous thing about that attack ad is not that McCain is accusing Obama of being a celebrity, it's that he doesn't realize that he is one, too. The difference: other celebrities don't love him quite as much as they do Obama. Which leads us to the Republican National Convention in St. Paul. The "cool" factor will be downgraded quite a bit, because actors and musicians have a lot more fun shaking the hands of Dems than Repubs. But I'm sure Heidi Montag, Spencer Pratt, and Jimmy "JJ" Walker will be more than welcome at the events.