When someone is invited to Aha!, they click on the link in the email invitation and it takes them to the login screen. The link says "I forgot my password" but as a new user I have not created a password so I am not sure what to do (The answer is to click on the link anyway, which will send a new link in email and allow one to reset [really create for the first time] a password).
This should be a high priority.. it's horribly un-intuitive.