By smearing Kerry via the Swift Boat front group the Bush camp wins tactical advantages no matter what happens. Even as the various bizzarro allegations by not-so-Swifties are being systematically proved to be a complete tissue of lies and are even turning off at least one high-profile media supporter, the whole flap is making Kerry spend money on a counter-ad — a very good ad but it's still money, and distracting people from stuff that matters.
[Update: How could I forget to link to swiftvets.eriposte.com, the comprehensive fact-compiling and checking site on Kerry & Vietnam!?!] [Update 2: this devastating letter from another swift boat eyewitness puts yet another nail in a well-nailed coffin.]
(Oh yes, even the Xmas in Cambodia mis-speak has a very rational explanation.)
It remains to be seen whether Bush/Cheney's tactical gains can be overcome by a strategic loss — which happens only if Kerry/Edwards can put the albatros of dirty pool around the Bush/Cheney necks.