If your lease ended 11/30, then you simply have to give 30 days notice and you can then move out. Make sure to notify the leaseholder that you are moving and that you wish to be removed from the rental agreement. Have someone help you draft your 30 day notice letter to the landlord so that it's in proper English and there are no misunderstandings.
I do not know if NY state allows you to give mid-month notice and to then pro-rate. I do not believe that they allow it, which means that if you give notice now, you will be responsible for rent until Jan 31, 2011. Call the housing board and find out what you are permitted to do. If they allow you to give a direct 30 days notice (as opposed to one full rental term), and you give notice tomorrow, then you will owe rent until 01/11/10 or 01/12/10.