We all eat spices that have been irradiated. This practice might make sense. People tend to buy spices and then stick them on a shelf for a long, long time. Little things growing in your cinnamon would not be yummy. It is probably not ideal (and it certainly encourages you to keep spices well past their flavor prime) but I can see how it might be seen to be the same as canning or other preservation methods. ( I think in the future there will be more interesting solutions that don't involve radiating something. )
But irradiated spinach? I am skeptical. While this is being proposed to reduce infection from E. coli, it seems likely that the real impetus is to keep fruit and vegetables fresh-looking for a little longer.
I am not a fan of many antibacterial measures. I think it is important to have our little bacterial friends around, and basically anything that kills off bad bacterial is likely to kill something good along the way.
Related: an interesting post about how we are being "protected" from E. coli in beef.