When Barack Obama declared "We are the change we've been waiting for," the pundits scratched their heads. In retrospect, though, it seems as if That One was onto something. For better or worse, we're living through a moment of intense transformation. In politics, the Bush years have been dustbinned. As far as the economy goes, the heady days of hedge-fund excess have been reduced to burnt toast. And from a Madonna standpoint, the Guy Ritchie era has been swept away. "The Power 40" reflects this whiplash-inducing volatility. Many of the usual suspects have been replaced with an array of wild cards and agents of change. A home-wrecking home-run hitter? Check. Tech guys who have all of tweendom a-Twitter? Yup. Buddhists with bombs? Uh-huh. This year proved you can never be sure of what comes next (hell, Chinese Democracy finally showed up, didn't it?). The whole point of power, after all, is to keep 'em guessing.

Power01_2 1. THE UNITED STATES SECRET SERVICE AGENT >>
Power02 2. NEEL KASHKARI >>
Bailout Czar
Power03_2 3. THE NATIONAL ENQUIRER REPORTER >>
Power6 4. BAITULLAH MEHSUD >>
Commander, Pakistani Taliban
Power05 5. THE PALIN BUNCH >>
Todd, Track, and Trig Palin,
Levi Johnston
Power06_3 6. THE BIPOLAR BROKER >>
Power07 7. TOM CRUISE >>
Leading Man
Power08 8. BARACK'S BOYS >>
David Plouffe, Campaign Manager,
Jon Favreau, Chief Speechwriter
Power09 9. THE GREENWASHERS >>
David Jones, Euro RSCG,
Christopher Barger, GM,
Matt Kistler, Wal-Mart
Power10 10. FERNANDO SÁNCHEZ ARELLANO AND HERIBERTO LAZCANO >>
Reputed Drug Kingpins
Power11 11. JOHN MAYER >>
Press Whore
Power12 12. THE HIPSTER FARMER >>
Power13 13. THE COMIC-BOOK GEEK >>
Power14 14. RAJAT AND JAYANT AGARWALLA >>
Scrabble Revivalists
Power15 15. MICHAEL RAPINO >>
CEO, Live Nation
Power16 16. THE BROKEN SOLDIER >>
Power17 17. LARRY RUDOLPH >>
Star Resuscitator
Power18 18. EVAN WILLIAMS AND JACK DORSEY >>
Cofounders, Twitter
Power19 19. ROBERT DOWNEY JR. >>
Actor
Power20 20. THE FAT BOY >>
Power21 21. JOEL OSTEEN >>
Pastor, Lakewood Church
Power22 22. THE HOLLYWOOD STRIKER >>
Power23 23. THE BADASS BUDDHISTS >>
Power24 24. NICK JONAS >>
Guitarist/singer, The Jonas Brothers
Power25 25. ALEX RODRIGUEZ >>
Third Baseman, New York Yankees
Power26 26. THE HACKTIVISTS >>
Moot, Anonymous, Rubico
Power26 27. BOBBY JINDAL >>
Governor, Louisiana
Power28 28. THE PREPPY >>
Power29 29. LIL WAYNE>>
Crossover Kid
Power30 30. CHINESE DEMOCRACY >>
Reclusive Rock Album
Power31 31. THE SPACE INVADERS >>
Zhai Zhigang, Jing Haipeng, Liu Boming, Astronauts
Power32 32. NATE SILVER >>
Statistical Soothsayer
Power33 33. ANDREW STANTON >>
Writer-director
Power34 34. ROCK BAND BROTHERS AND THE GUITAR HERO >>
Kai Huang, CEO, RedOctane
Alex Rigopulos and Eran Egozy, Cofounders, Harmonix
Powert 35. TOBIAS MEYER >>
Worldwide Head of Contemporary Art, Sotheby's
Power36 36. THE COLD WARRIORS >>
Mikheil Saakashvili, President, Georgia
Dmitry Medvedev, President, Russia
Power37 37. JUSTIN GASTON >>
Parents' Nightmare
Power38 38. R. KELLY >>
Singer
Power39 39. CLAY AIKEN >>
Gay American Idol
Power40 40. THOMAS BEATIE >>
Mr. Mom

PLUS:
Don't miss our Power Tools list of 2008's biggest losers, including Brett Favre, Mario Lopez, and Joe the Plumber.