Patrick, I'm really not sure about conversion tracking for AdWords, but I have a hunch... The Google Analytics module for Drupal adds traffic tracking in general to a Drupal site. Then there's the Google Analytics for Ubercart module (originally by Ny Media) which uses a Drupal hook to add the e-commerce information for completed sales to the GA form on the checkout page. My hunch is you can patch that module to add in conversion tracking information if that isn't what you're looking for there. Let me know what you find out. If we can roll it into core, that'd be great.