I just did some poking around the web. Apparently, it is still possible to get from home flocks, but the chances are greatly decreased. Free range and organic flocks test around 5%, while large, industial flocks can have 4 times that amount. Other random tidbits I picked up: it is estimated that the chance of the salmonella being in the egg is only 1 in 20,000. I believe this is different from it being on the shell, where it would be slightly more common. When it is in the egg, it is generally in the white, and only can get into the yolk when the egg gets old. So another bonus for our home raised eggs. Anyway, chances seem pretty darn small!