I have had this happen a couple of times and my experience has always been the the hotel will offer something in the form of compensation if you are polite and understanding.

This happened once at the Renaissance Mayflower in DC and the hotel comped me a very nice dinner in their restaurant.

Also had this happen recently at the Hilton Charlotte City Centre and the hotel comped me a drink in the bar, and also had a nice selection of sodas and snacks with a letter of apology waiting for me in the Suite when I arrived.