CNET is reporting that a bioplastics manufacturing company, Metabolix, has developed a genetically modified switchgrass that contains "significant amounts" of usable bioplastic in the leaves. Bioplastics are a very good thing, certainly, as plastic is normally made from oil in processes that are not exactly the most earth-friendly. Considering how quickly switchgrass can grow in the right conditions, it seems to me that this could be a tremendous source of more ecologically friendly plastic.
On the other side of things, though, I am, as are most gardeners, extremely leery of genetically engineered plants (this is part of why Park Seed carries none). It's difficult to predict how a new hybrid or non-native plant will behave, much less a plant that is fundamentally different from anything that's come before. Switchgrass spreads primarily by rhizomes, and any plant that spreads this way can be extremely difficult to control. I very much doubt that this plastic plant would make any significant widespread problems, but what local damage could commercial farming of it wreak? Most likely none, and I must be very careful to point out that I have no real reason to believe that this grass could be at all dangerous, and the benefits of further research are obvious (not to mention that the idea of plastics being farmed safely is very, very cool).
[Note: This blog expresses only the opinion of Thomas Andrews, and not that of Park Seed or related companies.]