It would be fabulous if the Obamas diverted part of the White House lawn to an organic vegetable garden. Why not, really? Lawns are fine, in moderation, but huge expanses don't make a lot of sense, ecologically or otherwise.
Kitchen Gardeners International has been using blogging and internet power to encourage this idea since WAY before our US election in November. And this idea won a non-profit contest for best initiative from OnDayOne.org.
And why shouldn't we try to grow more food in the city, as this link suggests? And those of us in rural and suburban areas, with available space, certainly why not?