yes, they do, both in your cabin and at dinner. However, you pay for it. I think the current charge is $3.50 for a large bottle. I usually buy one in port and take on board with me.
My last cruise was on Carnival, out of New Orleans - it was common to buy a case of water and carry on board - or two cases. They were sold right at the embarking location.
This thread sounds like RCCL may have a different policy -- I planned on carrying a case on board, does anyone know for sure if this would be prohibited?
I am not positive, but I think that RCCL would frown on seeing a case being brought on board. I guess it would depend on how it was carried on. We normally pack several bottles of wine in a suitcase and check it like luggage and have never had a problem. But, if we showed up with a case of wine in our hands as a carry-on, I suspect it would be denied.