This is a story from the UK and US laws are different, but a hotel that does not protect itself should not assume there is no legal liability.
Having a clear 'Terms and Conditions' or 'Usage Agreement' page requires some type of Public Access Controller (we strongly prefer HP's), but requiring a positive acknowledgement ('I Agree' button) and recording that acknowledgement are the only way to confirm that the guest user was informed.
http://www.guardian.co.uk/technology/blog/2009/nov/27/pub-file-sharing-cloud-fine