AWOL and Swift Boats
I don't care about Bush being (allegedly) AWOL from National Guard duty, yet I find the fact that Kerry wasn't (allegedly) in Cambodia and was (allegedly) given medal he didn't earn terribly important. Why? Because it is Kerry who is, and has been for the past 30 years, running on his record as a Vietnam War Hero. Without Vietnam, what exactly does Kerry stand for? Nothing.
Bush on the other hand is running on his foreign policy record. His days in the National Guard, like his days snorting Coke, are irrelevant.
Update: Instapundit has some good links, some of which suggest the memo used to nail Bush was probably a forgery.