>The first of two Soviet-centered specials this week is The Long Way Home (Discovery, Sun., April 29, 9 P.M. ET), director Michael (Coal Miner’s Daughter) Apted’s fascinating profile of Russian rock musician Boris Grebenshikov. It’s filmed in his native Leningrad and in London, Montreal and New York City, where Boris traveled to record the album Radio Silence in 1988. The following night PBS begins the four-part Inside Gorbachev’s USSR with Hedrick Smith (Mondays, 9 P.M. ET). The former New York Timesman conducts a detailed study of the dismantling of the Communist party hierarchy and the profound societal impact this policy has had.