And for all the bumps that his career has endured from box offices and critics, it seems clear from this year's celebrations that no one has stopped Sondheim. The songs on the PBS broadcast, lushly played by the Philharmonic under the baton of his devoted Paul Gemignani, are nearly all familiar, parts of the lingua franca of today's theater. Some of the performances seem a little familiar, too, mechanically touching the usual bases. But the best items, including a next-to-closing epic involving seven divas, reaffirmed that Sondheim, the guy who wrote the songs, lives on, excitingly. The kvetch who wrote the notes? Who remembers him?