You must have been one of the privileged few. I tried to sign up about a year ago but the service was only in very limited Beta (and apparently by invitation only). I signed up for g-mail alerts and just received my invitation this am.
I registered at gmail for information a year ago, but heard nothing. I found that the only way to get an account was to find a current beta user with extra accounts to give away. After having the account for a month I also got extra accounts to give away. A month ago it went up to 50!
So, if you want an account freep mail me your email and I'll send you one.
birddog