I would like to chime in and note that DWK's aging as dragons being commonly accepted means neither that it's right nor that it's what a DM would accept. In fact, the Dragonwrought feat does very little to the aging process of a Kobold: eliminating aging penalties and extending the ultimate lifespan of the kobold by a small amount. It does not cause you to gain age categories as a true dragon.
As for other templates, a fluff argument could be made for gaining the mental bonuses on-schedule for undead templates, and not taking the physical penalties. In pretty much every other case, however, there are simply no rules at all regarding what happens to a creature's age categories once you stick a template on it. Not even in Savage Species.