On March 19, 2008, Monsanto settled with Saskatchewan Farmer, Percy Schmeiser [pictured above], for their contamination of his farm with their Round Up Ready Canola [found via Deconstructing Dinner].
What does this mean and why is it important? Monsanto is a large multinational corporation that is the leader in genetically engineered seeds. The US Environmental Agency has labeled Monsanto as a "potentially responsible party" for more than 56 Superfund Sites in the US.
Monsanto has been very careful to control their seeds and how they are handled by farmers around the world. One argument against genetically modified crops is that there can be cross pollination between crops [ie some genetically modified crops might cross pollinate with the organic crops next door, negating the organic status of the crop]. This settlement with Percy by Monsanto is a step in linking liability of contamination to Monsanto.
From what I know so far, I believe companies like Monsanto threaten sustainability, by threatening small farmers, local community based farming, and contamination of organic farming. Their continued efforts towards genetic modification [with properties like terminator seeds] and seed patents are impediments to larger efforts towards a sounder ecologically responsible society.