We've had several interns, most of which were from Canada (University of Waterloo apparently has strict experience requirements for undergrads). There's not too much of a challenge - contact different startups, you'll be sponsored, you'l come here and be put through some immigration unpleasantries, and go home at the end of three months or so.

Give it a try! HN is only one route to find internships - check with friends, online contacts, and your university to see if they have any placement program.