I've just gotten a gmail acct myself. Awaiting the invites... Mailing like crazy (apparently you get invites based on the number of messages sent/received).
Won't be long until it's opened to the public to join freely, I reckon.
Thanks Guys, I just got my acct from a work college. He said that the more invites that he sends out, that are signed up successfull, the more invites he gets.