“Among those whose music-making produced a level of beauty, insight and involvement practically alien to the present, cellist Gregor Piatigorsky will always be regarded highly.” But with the decline in classical record sales and a general ’embrace-the-new’ attitude in classical music, how many listeners really know Piatigorsky anymore? However many it is, the number should increase soon. Piatigorsky would have turned 100 this month, and several Baltimore-area arts organizations are celebrating with concerts, exhibits, and remembrances from family, friends, and colleagues.