Software in Canada is second class - salaries are nowhere near the US levels, and much of the work is "scrap" from Americans.
Everywhere I look in Canada I see satellite offices to large American software companies. Invariably these offices do the boring, mundane code that nobody wants to pay $150K to a Californian to do. That's what I mean when I say "scrap" - monkey work, not real dev. It's hard to find a Canadian shop that writes real, meaningful code.
For tech companies focusing on mobile apps this is especially troublesome. Telecommunications in Canada is expensive as hell, and come with a ludicrous number of strings attached. Want to do a high-bandwidth site like Hulu? Forget it, your customers get hit with overage fees from their ISP like the plague. Want to do a mobile app? Sky high costs for data plans means your customer base is severely limited, and even the ones that do have it are apprehensive about going over their paltry (500MB to 2GB!) monthly limits.
I wouldn't consider doing a Canadian startup that sells to Canadians. I would, however, consider a Canadian startup that sells to Americans :)
If I could bear the cold I'd skoot over to Toronto in the blink of an eye.