Hardly Strictly Bluegrass has never been about full-tilt traditionalism and musical purity, though real-deal legends like Ralph Stanley and Earl Scruggs, plus true believers such as the Del McCoury Band and the Roan Mountain Hilltoppers, have always graced its stages. Here are a few new, yet somehow familiar, and irreverent faces to the Golden Gate Park bash. (Kimberly Chun)

BONNIE "PRINCE" BILLY

Don't get Will Oldham started on these whippersnapper actors today. When the subject of promising thespians came up during our recent interview, I suggested Shia LaBeouf. "I heard going into [Indiana Jones and the Kingdom of the Crystal Skull] that he was good, but it was awful and he was awful," said the Matewan child star, who saw it in Corte Madera during his recent Headlands Center for the Arts residency. "It was awful in the same way the first new Star Wars was awful — it seemed like it was designed to create the video games that were accompanying it."

Sun/5, 1 p.m., Rooster Stage

LOS CENZONTLES WITH SANTIAGO JIMENEZ

The Chicano band's moniker may translate as the Mockingbirds, but there's no mocking these activists' grasp of Mexican roots sounds, including Tejano and Son Jarocho. Traditional folk instruments like the uke-like jarana will mingle with Jimenez's Tex-Mex squeezebox stylings.

Sat/4, 11 a.m., Arrow Stage

HEAVY TRASH

Tube amps burst, echo machines eke out, and rockabilly kittens swoon when groovy-hate-fuck cats Jon Spencer and Matt Verta-Ray bend those badass notes.

Sun/5, 5:45 p.m., Star Stage

THE INFAMOUS STRINGDUSTERS

Three prizes at last year's International Bluegrass Music Association Awards went to the combo.

Sun/5, 2:10 p.m., Arrow Stage

IRON AND WINE

A long-tressed Sam Beam and his Wine-ers broke onto Letterman with The Shepherd's Dog (Sub Pop, 2007). So what's next?

Sun/5, 3:25 p.m., Rooster Stage.

MARK OLSON AND GARY LOURIS

Two forces in the criminally unrecognized Jayhawks reunite — long after vocalist Mark Olson moved to the Joshua Tree area to be with now-ex Victoria Williams. Coming on the heels of Louris' Vagabonds (Rykodisc) is their new Chris Robinson–produced collabo, Ready for the Flood (Hacktone).

Sat/4, 1:30 p.m., Rooster Stage

ROBERT PLANT AND ALISON KRAUSS

The warmth and intimacy of this simpatico musical coupling was enough to ward off the chill at this summer's foggy show at the Greek Theatre as the lion-maned duo tamed the Zep-happy mob with hushed versions of "Black Dog" and "The Battle of Evermore."

Fri/3, 5:15 p.m., Banjo Stage

WACO BROTHERS

OK, these yobs are far from unknown: Jon Langford and Steve Goulding can be sighted among the many Mekons, and Alan Doughty survived Jesus Jones. Good-timers like "Drinkin' Cheatin' Death" show why this band drives its hometown Chicago crowds nutty.

Sat/4, 12:05 p.m., Star Stage

PEGI YOUNG

Neil Young spotters will hope he'll sit in, but give the woman who masterminded the Bridge Benefit her due. Pegi's self-titled debut (Warner Bros., 2007) found her stirring from the support role, wrapping sugar-dusted, languorous tones around slow-dances à la "When the Wildlife Betrays Me."

Sun/5, 4:30 p.m., Arrow Stage

Hardly Strictly Bluegrass 8 runs from Fri/3-Sun/5, in Speedway Meadow, Golden Gate Park, SF. Free. www.strictlybluegrass.com.