The 2009 Bonnaroo Music and Arts Festival unfolded under threatening Tennessee skies last weekend as 75,000 fans — including Drew Barrymore and ”ex” Justin Long — enjoyed intense side-stage shows from Public Enemy and the Yeah Yeah Yeahs and rocked out to headliners like Bruce Springsteen and the E Street Band. (Bonnaroo ticket: $275. A ”Santa Claus Is Comin’ to Town” sing-along in June? Priceless.) The reunited, rejuvenated jam-rock heroes of Phish played two nights of light-show-enhanced improvisations and crowd-pleasing covers: Friday’s set included AC/DC’s ”Highway to Hell,” and on Sunday they were joined by the Boss himself, who sat in for euphoric bar-band renditions of ”Mustang Sally,” ”Bobby Jean,” and ”Glory Days.” All together now: PHRUUUCE!