“This is hip, pretty baby.” John Lee Hooker is singing ’bout love. But he could be assessing the current state of the blues. The root of all things pop, from jazz and rock to country and hip hop, the blues is still flourishing after all those hybrids, as new releases from three generations of bluesmen show. While Hooker, 81, joins forces with younger disciples like Eric Clapton and Bonnie Raitt on The Best of Friends (Pointblank/Virgin), blues babe Jonny Lang, 17, argues that age and race mean little—you either got it or you ain’t—on Wander This World (A&M). He can’t muster the knowing growl of his elders, but Lang’s virtuoso guitar talents would impress the king himself, Robert Johnson, whose posthumous 1961 album King of the Delta Blues Singers (Columbia/Legacy) is reissued with a startling addition: a never-before-heard version of “Traveling Riverside Blues.” One of 29 songs that make up Johnson’s entire oeuvre, the track, recorded in a Dallas hotel in 1937, was recently discovered in archivist Alan Lomax’s Library of Congress collection. Though this may not unlock the myths surrounding Johnson, whose 1938 murder remains shrouded in mystery, it will surely add to his legend.