If you can’t refuse business, then you don’t really own your business. I mean, I think they should have charged a premium and taken the money, but certainly it is their right to do so or not.
If you are generally open to the public then you cannot deny your products/services to certain protected categories such as race, sex, etc.
Sexual orientation has now been added as a special category, if not explicitly then at least implicitly by the ruling on DOMA.
The interesting thing will be to see if some more radical gays get too far ahead of the official gay agenda. If the radical gays can cool their heels for a few years then most businesses will be OK with serving gays. Then the few odd Christian hold-outs will just look like backward yokels. However, if some of the more radical types start pushing on this too fast then it could cause a backlash.
It almost makes me suggest that Christians should dare the more ardent gays to go for it in order to cause a backlash.
What happened in the 60's after the Civil Rights laws were passed? Were there motel operators that considered it a sin to give a room to a mixed race couple? Were they supported by their communities or were they drummed out of business?