The deadline for check in has been met. The Department of Transportation has some minimum amounts and guidelines for compensation on US domestic flights. If your airline can get you to your destination within one hour of your original time, no compensation is due. On international flights the airline has up to 4 hours to get you on a flight. Overseas amounts are determined by the tariff rules.
Airlines reserve the right to cancel or delay flights at the last minute.
They also are not required to provide meals, phone calls, or hotel rooms. If the delay or cancellation occurs due to weather, they most likely will not provide anything at all to ease your delay. Mechanical problems also do not require compensation, but the airline is most likely to do something. Involuntary Rerouting is the most likely action an airline will take. This simply means they will try to get you on the next available flight or on a different airline.