As a tried and true member of Generation X I can't argue with the results.

A few things that that stand out:

September 11th is the biggest event in the lifetimes of people born 3 generations apart. That says a lot
Despite our current Idiot In Chief's insistence that his inauguration was the biggest of all time, it will be remembered as a shameful day in America. Obama's on the other hand was one of the defining moments in our culture's history.
If there's one thing that ties each generation together it's the presence of war. WWII, Vietnam, the Gulf War and Iraq/Afghanistan all feature prominently on each respective list. We as a society should try and change that.
The lists are evenly split between some of the darkest days in our history and events that brought about amazing positive change. WWII and the Civil Rights Movement. Iraq and Gay Marriage.

Maybe in 20 years the next generation will have a list of nothing but things to be proud of. The way we're headed right now though I fear it will be exactly the opposite.