Used to be you could plant your feet smack-dab in the middle of the Mississippi Delta town of Clarksdale. Say at the corner of Fourth and Yazoo. Used to be you could swing a dead cat around your head. Swing it around and around. And that dead cat wouldn't hit a soul.     But time are changing down where cotton was once king, down where the blues was born. Clarksdale is now chockablock with hipsters on the lam from Manhattan and with true believers from Japan.     Over a lunch of stewed pork neck bones and black-eyed peas at Turner's Grill, they're plotting an evening of

drinking and juking. James "Super Chicken" Johnson and the Fighting Cocks are gigging at Smitty's Red Top Lounge. And actor Morgan Freeman - who calls the nearby town of Charleston home - has opened a fancy-schmancy restaurant, Madidi, and a seperate blues club, Ground Zero, which, despite its lack of provenance, boasts a gritty appeal and has the good sense to serve Champale for two bucks a quart.     When it's time to bed down, visitors have two worthy choices: the raffish Riverside Hotel, a black hospital during the days of Jim Crow and now a proto-funky flophouse-cum-motel; or the Shack Up Inn, a collection of four refurbished sharecropper shotguns, set on the grounds of the old Hopson cotton plantation.     Sunday-morning salvation is entrusted to Reverend Willie Morganfield, first cousin to Muddy Waters and pastor of the Bell Grove Missionary Baptist Church. He welcomes blues pilgrims with open arms. But do your mama proud: Dress nice, drop a ten-spot in the collection plate, and pay heed when he shouts from the pulpit, "Jesus is an air conditioner in the fiery furnace of hell!" - JOHN T. EDGE