[huxley]

Not sure about the US but it's possible he's referring to Monsanto vs Schmeiser, a Canadian case.

http://en.wikipedia.org/wiki/Monsanto_Canada_Inc._v._Schmeis...

In that case, Schmeiser's field was contaminated by his neighbour's field which was planted with Roundup resistant Canola seed.

"... on the balance of probabilities, the defendants infringed a number of the claims under the plaintiffs’ Canadian patent number 1,313,830 by planting, in 1998, without leave or licence by the plaintiffs, canola fields with seed saved from the 1997 crop which seed was known, or ought to have been known by the defendants to be Roundup tolerant and when tested was found to contain the gene and cells claimed under the plaintiffs’ patent. By selling the seed harvested in 1998 the defendants further infringed the plaintiffs’ patent."

[planetguy]

Right, so it's not that they'll sue you if their seeds blow onto your property, it's that they'll sue you if their seeds blow onto your property, you harvest, separate and and save the seeds from the plants that grow, then you plant 'em.

I'm still not sure that counts as infringement, but hey, who am I to disagree with a Canadian court's interpretation of Canadian law?