I think this should be the next Obama ad:

John McCain is lying to you about Barack Obama    and his plan to cut taxes for the middle class. According to factcheck.org, McCain is claiming "that Obama would 'raise taxes on (the) middle class.' In fact, Obama's plan promises cuts for middle-income taxpayers" making less than $200,000. 

While McCain tries to distract you with false accusations and tabloid hype, Obama is working to make America's economy stronger by providing tax relief to the middle class and additional tax rebates to American workers.

The McCain camp is calling out Obama for what they claim to be dishonesty (CNN):

"It's now clear that the Obama campaign's attack on John McCain and the
DHL issue -- which Obama campaign manager David Plouffe called 'the
most important development in the campaign' -- is based on a lie.
-McCain spokesman Brian Rogers

It's only fair that the favor be returned.

Also, this is a way to push back on the celebrity thing by showing how ridiculous it is in a more substantive context.  The message of this ad isn't just that McCain's lying, it's that lying and name calling are all he's got.