According to occupyboston.com the Boston Police have laid down an ultimatum. From the site:
At approximately 18:00 the Boston Police Department informed Occupy Boston that if they did not clear the site by nightfall, they would be forcibly removed. In response, Occupy Boston has issued a renewed call for any and all people to join the occupation as soon as possible. From the beginning, occupiers have worked tirelessly to maintain a positive working relationship with city officials. Today’s threats by the Boston Police Department represent a sudden shift away from that dialogue. Since making camp on September 30, Occupy Boston has maintained that it will non-violently resist any attempt to end the protest before we have achieved the change we seek.