I have never understood why I need to type my password twice. Inevitably I just copy what I wrote in the first box into the second. I'm also interested in the elimination of the post sign-up confirmation email. I'd rather get a "Welcome! If you didn't sign up for this service, click here" email, but I can imagine that if I didn't actually sign up for the service, I'd never want to "click here" for fear of spam. There…
It's especially important because a streamlined workflow will have both forms on the same page. It's infuriating to try to log in and get an "account already exists" error. HN is one of the very few sites that make this mistake.