Wow, Huhsmail was pretty silly with their claims:
the company that provides Hushmail, states that it will not release any user data without a court order from the Supreme Court of British Columbia,
This is malarkey. Someone in the US could say "I'll fight all the way to the Supreme Court!!!" but you would be a fool to trust your business to their determination. Especially if they say it about a subpoena, which means they haven't even retained a lawyer to ask about this. (If your business plan depends on being able to wage a legal battle, you really shouldn't be scrambling through the yellow pages for a lawyer when you get your first subpoena.)
Back to the topic, I'll have to point out that this still isn't evidence of a company being required to backdoor a product. Hushmail, the same company that thinks it can fight a subpoena for third-party data all the way to the Supreme Court, said "well, we might be compelled to backdoor our product." This is just more repeating of the meme without evidence. It's unfortunate because some developer who remembers Hushmail might take their ill-informed legal opinion as reality.
Of course, Hushmail had access to cleartext copies of the messages. That's the killer. The government has the right to evidence about third parties in your possession. (Canada derives from British law tradition like the US. The government's right to all evidence is a concept that goes back centuries. If you can show that Canada broke from this tradition I would be most interested.)