Not to knock on folks that use a dishwasher, but if you do, I'd recommend running a seperate cycle from other dishes and know that if you use Jet dry, or a detergent with a sheeting/drying agent, that this can kill head retention.
Personally, I started out doing this and no longer trust it. There's just no way much water/detergent is getting up inside those bottles. You're pretty much relying on the heat to sanitize and I'm not sure that's really up to snuff across all makes and models.