yes, people milk their shorthorns, while they are basicly the same breed, there are two types of shorthorns. the ones people millk are milking shorthorns and should be added to your dairy breed list. they have seen a significant rise in numbers as they are considered a dual purpose breed and are the prefered breed for homesteaders and 4-H working steer programs. beef shorthorns are also rising in numbers, as they are better milk producers thus their calves gain faster, and also can be used in the working steer program. thus shorthorns are a triple purpose breed.
dual purpose breeds would also include devons, belted galoways, and dexters.
there are over 800 breeds of cattle, but i suspect holsteins and angus are the top two, followed by jersey, shorthorn and hereford.
I feel as if beef shorthorn are MUCH more popular than milking shorthorn. True, many homesteaders do shorthorns, I would say in the purebred world shorthorns are very bottom in popularity. Mainly because their eye appeal is lacking. They are farther behind in development than the traditional dairy breeds. Many people cross Holsteins or Swiss with Shorthorn to improve leg, aid in fertility issues, or as a last resort.