Embraced is a momentous meeting of keyboard giants. Mary Lou Williams (1910-81) was, in fact, a one-woman history of improvised piano styles who also happened to be a first-class arranger and composer. Cecil Taylor (b. 1933) is nothing less than the most galvanizing and controversial piano improviser of, the past 40 years. Williams and Taylor, sometimes accompanied by bassist Bob Cranshaw and drummer Mickey Roker, joined forces before a live New York audience in 1977. While there are instances when they are not quite in sync., the two pianists often set off a kind of thunder and lightning that shakes improvised music to its very foundations.