To try to help against the unwinnable war against spambots making user accounts we've thrown email validation up. The main problem is that yahoo.com is blocking all email coming from any of the perception sites. This is an exceptional pain in the ass for a new user that has a yahoo email account that never receives his validation email or forgot password emails.
I've had this as an open issue with yahoo since november but they have yet to correct it. So I know there's a lot of word of mouth stuff going on for new users so if one of your friends is having problems signing up make sure to tell them to use a different email service than yahoo.
Plus gmail is the shit.
