As the debate goes on about who is running the most negative campaign, there is an important distinction.
Without question, the Obama campaign has ran negative ads, mailers etc. against McCain. But the difference is that Obama's negative ads are about issues, and McCain's campaign positions. The Obama campaign has gone to some lengths not to attack McCain personally or his patriotism.
The McCain campaign on the other hand, has been assaulting Obama's character and patriotism for months ("rather lose a war...", "Paling around with terrorists..." etc).
There is a difference, and it's not a media invention.