以下是其中一个“被黑”版本的作者写道：
In particular CURLOPT_SSL_VERIFYPEER
and CURLOPT_SSL_VERIFYHOST are true by
default: I set them to false and it
worked for the test page!
The effect that has is to pretty much negate any security advantage offered by using HTTPS. The primary reason HTTPS is useful in OpenID is that it guards against a man-in-the-middle attack, i.e. some bad guy poisons your DNS cache to send all google.com requests to bad-guys.example. With properly configured HTTPS, you'd verify the certificate on the connection, find out it wasn't from Google, and say "I'm not going to believe anything you say, bad-guys!"
Unless, of course, you don't verify any certificates (you set all the SSL_VERIFY options to false), in which case your server will believe everything bad-guys says as if it were the real Google provider. You can imagine how that might be bad.
Now, frankly, this isn't the worst choice you could make, because it's no worse than just using HTTP, which a lot of people do anyway. You're just lying to your users if you imply that you're providing HTTPS-level security when you're not.
And there's a lot of information out there about how easy it is or isn't to do a dns-based attack, or how easy it is to forge SSL certificates. Either way, it does require someone to attack the connection between your server and Google, which is generally harder than attacking the connection between the user's laptop in the coffee shop and your server.
But still, much better to actually fix your PHP or CURL SSL configuration. Or if you don't, warn your users of that when they sign up with HTTPS identifiers, so they can choose if they really want to use that OpenID with your site.
Which leads to your second question. I think, not knowing anything about which server platform you're using, the best thing I can do is to link you to the Curl docs on SSL certificates; see the section that says "Get a better/different/newer CA cert bundle!"