Mice Direct is now irradiating all its reptile food products in response to the recent discovery that some of the recent shipments may contain salmonella. This is the same process used on food for human consumption. Here is a link to their website with more information.
I wouldn't worry too much about salmonella in feeder rodents. It's not going to hurt your snakes and if you wash your hands with soap and water (and don't put mice in your mouth) you have virtually no chance of getting salmonella.
Learn more about salmonella at http://www.cdc.gov/salmonella/.