Bono and his band of merry men are not ones to miss a window of hope. And so on the eve of Barack Obama's inauguration -- just hours after the Irish rock ambassadors entertained the president-elect with their MLK Day anthem and their unofficial post-9/11 elegy at the Lincoln Memorial -- U2 unveiled a new single. Way to claim your spot on the "Yes, We Can" caravan, boys!"Get on Your Boots" is a first taste from the band's new long-player, "No Line on the Horizon," which hits the global marketplace Feb. 15. Hear "Get on Your Boots" and read details about the album (Most exciting tidbit): The digipak edition will include a film "companion to the album" by Anton Corbjin.Initial thoughts on the band's newest inspirational Pundits are already splitting hairs about "GOYB" -- does it sound like Elvis Costello circa "Pump It Up" or the Temptations classic "Ball of Confusion"? Both connections are plausible, and there's also a fuzzy Stooges-style guitar riff that would have made Ron Asheton chuckle. But the fusion "GOYB" represents is hardly new for U2 or longtime producers Brian Eno and Daniel Lanois.

U2 got its mojo back with "Achtung Baby" 15 years ago by realizing that as white guys, they had to loosen up and get a little dirty if they wanted to explore black-invented sounds. Since then, one of its many missions has been to meld rock and soul in a way that doesn't feel retro and honors both traditions.

"GOYB" is sharper-edged than "Mysterious Ways," faster than "Elevation" and more non-linear than "Vertigo." It's dance-rock with a few small, tricky changes: a very Eno-esque bridge to nowhere, based on the phrase "you don't know how beautiful you are" that drags out the beat like Silly Putty, and a break near the end that has Bono rapping "let me in the sound" over a muscular Larry Mullen Jr. drumbeat that yells "I love rock and roll!"

As usual, modern rock's beloved grand uncles have been absorbing the lessons taught by their progeny. "Get on Your Boots" is quick and multi-layered, more like the dance rock preferred by kids who grew up on electronic music than a baby-boomer boogie fest.

Though it's tempting to stir up a rivalry between the alt-rock era's most beloved British band and its iPod-era successor, "Get on Your Boots" sounds nothing like Radiohead. MGMT seems like a more relevant influence. This is happy stuff, almost hedonistic, with not a whiff of anxiety or paranoia or even sexual tension. "Get on Your Boots" is a song about letting loose and letting go.

And moving toward a brighter future. Bono's musings here do not read well on the page (peruse them here, if you must), with Bono cutting up phrases he's used before and free-associating like he's had a couple of pink cocktails. But the underlying message is relevant.

So what is sexy about donning boots, in a song whose cheerful tone and other lyrics about forming community and growing up hardly suggest a pair of stilettos? To turn a phrase that once belonged to the increasingly irrelevant Paris Hilton, it's hot right now to ponder cleaning up a mess. And that's what "Get on Your Boots" means to inspire us to do. This is U2's celebratory announcement of a new historical moment, one in which America and the world confront the catastrophes of the recent past and bust out some elbow grease to make things better.

It's not quite time for a new anthem, this song seems to say, though titles from "No Line on the Horizon," like "Cedars of Lebanon" and "White as Snow," suggest those are coming. It's time to get to work. In its playful way, "Get on Your Boots" is a work song, a little jolt for those ready to rise up together toward change. Let me in the sound, indeed.