Ye' old general discussion board. Basically, for everything that isn't covered elsewhere. Come here to shoot the breeze, shoot your mouth off, or whatever suits your fancy. This forum is not for asking programming related questions.
I normally re-enter the password just to make sure I haven't made a stooopid mistake. The same applies for when you're asked to re-enter a chosen password on a registration form.
I don't think they are completely useless, but they are not 100% reliable either. If a user sees that they need to re-enter a bit of info then they will normally pay a bit more attention to what they are typing.... even if they do just copy and paste it.
I've been watching people (including my friends) filling forms on my school's lab (we developed a survey about some of our intranet's new features last week). I saw many of them (above 70%) doing exactly as devork describes above.