The FDA announced on the 29th that all spinach implicated in the current outbreak has traced back to Natural Selection Foods LLC of San Juan Bautista, California. They have not yet identified the field or fields (if that's the ultimate origin) or whether the contamination arose from the handling of the spinach at the NSF processing plant. So far, it still looks to me like a small spot contamination spread nationally. The state of Washington has experienced E. Coli contamination of raw milk, the same O157:H7 strain that is particularly virulant. Is it industrialized processing methods? Or, are the little bugs evolving? It doesn't take much to get infected. The FDA reports: Infective dose -- Unknown, but from a compilation of outbreak data, including the organism's ability to be passed person-to-person in the day-care setting and nursing homes, the dose may be similar to that of Shigella spp. (as few as 10 organisms).
Here's a 1997 map depicting the 157:H7 isolates by state showing it appears in many places.
Compare that with the states reporting cases of E. Coli outbreaks; it's nearly universal.
...and yet the number of people infected is vanishingly low (1/20th Salmonella), far lower than injuries and deaths by automobile. It is even far lower than many other diseases (see http://www.disastercenter.com/cdc/disease.htm for the list). It is peculiar that which people perceive as dangerous since it has little bearing with the actual rates.