Yes a great loss.
I actually had him come in and teach when I was studying Jazz at York University in Toronto. I've also seen him play a number times back in the late 80s. I also was lucky to see him play with Ray Brown and Herb Ellis when they were doing a trio reunion. I think that was at a place called the Bermuda Onion which is alas like most of the great Jazz venues in North America is also no more.
There was a big free concert at Roy Thompson Hall last night in his honour. You can hear the concert here:
Welcome to CBC Radio Two
More on Oscar here:
CBC Radio 2: Oscar Peterson 1925 - 2007