TV: Mad Men, the Wire, Sopranos
Film: Charlie Kaufman, Tim Burton, Kathryn Bigelow, Todd Solondz
Literature: Jonathan Franzen, Dave Eggers and McSweeney's, Don De Lillo
A black presidency, and the networking-based campaign that got it going (admittedly the second part owes something to S. Korea's)
Facebook, Twitter, and social networking sites
The Tea Party (OK, so you don't like it, but it is still an important innovation)
The campaign against the Iraq war
Seattle and the anti-capitalist campaign