I work in the Canadian finance industry, so I won't be immediately affected by the US sub-prime lending woes, but I suspect that we as a country will begin to experience similar lending issues in a year or two.
My key concern regarding this sub-prime issue is American consumer spending, which is a huge driver of your economy, as well as Canada's. I think that we will see a tightening of lending standards in both the US and Canada, which means less money supply to consumers, which in turn means flat or lower housing prices. I think that a decrease in consumer spending would ultimately (indirectly) affect commodity prices, which wouldn't exactly be a good thing for Canada.
I could very likely be mistaken, but I suspect that some of these sub-prime woes are part of the reason for stock market issues this week...there could be some fear that this is just the tip of things to come.