So...many big stories...in such a short time: 2010!
I would say the BP Oil Spill...although I know they (BP) wish it would just disappear into obscurity...and folks wouldn't mention it.
The next question...based on what big events that have happened over the past year(s)...is what big story lies ahead for 2011...could be kind'a scary...if you look at it in regards to recent years...as to what might happen next!
Great question and all the major ones have been listed. BP oil spill ranks #1 in overall magnitude. The Chilean miners story #1 human interest story. Haiti earthquake response was big, but the cholera outbreak (in my opinion) is a bigger story.
SF Giants winning the World Series was pretty huge (regionally, anyway).
The tea party phenom... (hopefully a flash in the pan).
Speaking of baseball, here in Texas it was major news that the Texas Rangers went to a World Series and actually won a game. I never thought I'd live to see that. When the Rangers went to the World Series, I told people that those in hell are looking for electric blankets and space heaters because they'll need 'em if the Rangers win. LOL