David Weinberger, author of "ClueTrain Manifesto, posits an interesting thought provoker here. In 50 years, when our grandchildren look back on how we conducted our life and culture in the early 21st century, what will they be amused/horrified by?

My ideas:
American arrogance in global affairs (neo-imperialism)
Antagonism (civil/social/religious) towards non-hets
Failure to constructively engage the developing world
The inequities of capital punishment