I have a Google Account. Why can’t I sign in to Google Wave?
This is what they told me when I tried to log in:
Even though you have a Gmail or a Google Account, you must be invited to Google Wave in order to sign in. If you haven’t been invited by a friend, you won’t be able to use the service at this time.
If you have been invited, but you aren’t able to sign in, make sure you follow the link in the email invitation the first time you want to access the service. You must use your unique URL to sign in to Google Wave the first time.
Google Wave is currently available in a limited preview release. If you’d like to sign up for updates about Google Wave’s availability, please fill out this form. If you are a Google Apps administrator and you are interested in using it on your domain, express your interest here.
And this is what the register form looked like <<form>>