That looks like cellulose to me, but I'm not an asbestos expert.
The only way to know for sure if it contains asbestos is to have a sample tested by a lab which specializes in asbestos identification. You can usually find at least one of these labs in larger towns and cities.
"The physician can bury his mistakes, but the architect can only advise his clients to plant vines." -- Frank Lloyd Wright
fabrk8r is probably right... if it is just the loose batting over the joists in your attic its likely just cellulose. Asbestos was more often used in a spray form (sprayed on concrete) or wrapped around pipes/ducts to insulate them... or in drywall compound... or tile... or... etc....
However, a lab is the only way to be sure if you're really concerned. Be prepared for a whopper of a bill though.