New York City marked the end of the clean-up of the World Trade Center site this morning, with a service that paid tribute the the victims of the 9-11 attack. The day was also a chance for the workers and volunteers at the site to say their goodbyes. Lisa Poseley has volunteered at a ground zero canteen nearly every day since September 11th. She grew up in Minnesota but has lived and worked in New York for the last four years. She was at her apartment just 12 blocks north of the World Trade Center on the morning of the attacks. We spoke with Lisa about her experience volunteering at ground zero in early January. Today, we caught up with her on her cell phone from the site. She says the ceremony this morning was bittersweet: