Not sure about every channel being HD, and not sure how they are doing it, but Shaw has a highdef signal on (Classic channel 103) Sportsnet East HD..which is on F2, usually; and is obviously not coming from there now.
I had sports on most of the night up until well over 8:30 pm Atlantic and didn't notice the problem until I changed channels.. As someone else pointed out, most of the HD Canadian nets are on the third satellite, so my guess is that TO and Vancouver signals are being substituted with signals from other cities for those of us that are able to receive them. (eq. 6XX receivers). I can definately tell the difference between HD and SD.