Oscar Peterson is the most famous jazz musician from Montreal, and probably from Canada, in fact. He was one of the greats, certainly. And I don't mean this as a slight in any way, but I'm not sure that his will be the longest-lasting influence. I think Paul Bley's is, and will be, more significant for two main reasons: his conceptual contributions, and the importance of the people that he shared them with during his astonishing career. Aside from Miles Davis, I don't think anyone has a list of collaborators with the diversity of Bley's: Charlie Parker, Charles Mingus, Charlie Haden, Ornette Coleman, Pat Metheny, Chet Baker, Bill Evans, Gary Peacock, Carla Bley, and many others. Not only is this list of giants impressive on its own, but it seems as if Bley was involved with them at pivotal moments of their careers, and therefore of jazz history itself. A good place to learn about Bley's work is his 1999 autobiograpy, Stopping Time: Paul Bley and the Transformation of Jazz. It's surprising, insightful, funny and moving: sort of like his music. Here's "When Will the Blues Leave?" from his 1962 album, Footloose (with Steve Swallow and Pete LaRoca) one of his great trio recordings and a major contributor to the style of Keith Jarrett, among others: http://www.youtube.com/watch?v=kyjis-gBwAM.