that was a first time for me, hopefully not the last.
we've seen it here, lots of negative connotations surrounding snakes.. particularly the only one that is venomous in Ontario. this little guy was not threating at all, just letting us know that he was in the area and to watch your step.
while i am sure getting bit by one would be very unpleasant, they are protected/endangered and it'd be a shame to lose another species. just be aware that they do exist (particularly in the bruce peninsula and eastern shore/islands of georgian bay). if you hear a rattle, stop, don't panic, find the source of the sound and back away. they are not (usually) aggressive. they eat frogs and other small animals, you are hardly on their menu. you'd more than likely have to step on one or try to pick one up to get bit.
if you do get bit, it's not a death sentence - though definately seek medical attn. they don't always inject venom, particularly if they don't view you as food and a young snake is more likely to hit you with more venom than an older one. parry sound and i believe, midland hospitals have the anti-venim on hand. i understand it only works once.
i've read that there have only been 2 fatalities attributed to rattler bites in the history of ontario. if that warrants eradicating them, then i suggest you stay off the highways.