I've only been once. They were giving away 6'ers of Black Thunder as a promo but I don't know if they have a brewpub license or production brewery.
@aschwab would probably know how Austin Beerworks is licensed. And possibly would have been to the brewery and know if they normally have 6'ers.
No. They have a brewery license and can only sell for onsite consumption. No growlers, crowlers, or cans to go.
I am more offended by "Austin City Beer Works" than anything else. No, it would be against the law for them to sell 6ers. But, they are available at pretty much any beer store/grocery store in Austin.