I was wondering the same thing and came across these. Not specific to swine flu virus though.
Flu germs: How long can they live outside the body?
If someone has the flu or a cold and coughs into his hand, and then he touches a doorknob, how long can those germs live on that doorknob?
from James M. Steckelberg, M.D.
The length of time that cold or flu germs can survive outside the body on an environmental surface, such as a doorknob, varies greatly. But the suspected range is from a few seconds to 48 hours — depending on the specific virus and the type of surface.
Flu viruses tend to live longer on surfaces than cold viruses do. Also, it's generally believed that cold and flu viruses live longer on nonporous surfaces — such as plastic, metal or wood — than they do on porous surfaces — such as fabrics, skin or paper.
Although cold and flu viruses primarily spread from person-to-person contact, you can also become infected from contact with contaminated surfaces. The best way to avoid becoming infected with a cold or flu is to wash your hands frequently with soap and water or with an alcohol-based sanitizer.
How long can viruses live outside the body?
We know that some viruses and bacteria can live 2 hours or longer on surfaces like cafeteria tables, doorknobs, and desks. Frequent handwashing will help you reduce the chance of getting contamination from these common surfaces.
What is the mode of human-to-human transmission of the swine flu virus? How long does the virus live outside the human host — i.e., on objects (like door handles) and in the air (for instance, on dust particles)?
— Andy Beckerman
The swine flu virus is transmitted the same way other flu viruses are spread, according to the Centers for Disease Control and Prevention. The most common method of transmission is airborne — being in fairly close proximity to an infected person who is coughing or sneezing. It is also possible to become infected by touching a surface with a flu virus on it and then touching one’s mouth or nose, which is why experts advise people to wash their hands frequently and avoid touching their face.
How long a virus can live on an object like a door handle or in the air has a lot to do with temperature, humidity and sunlight, said Dr. Layne of the UCLA School of Public Health. The hotter it is and the more the virus is exposed to sunlight, the shorter it is likely to live, he said. Humidity can have variable effects, sometimes prolonging and sometimes shortening the life of a virus. The C.D.C. says some viruses and bacteria can live two hours or longer on cafeteria tables, doorknobs, desks and other surfaces.