After setting up a valid email addy at gmail- and getting a confirmation code sent to my cell phone, and alternative email address, I logged in, using my email and password.

It gave me this screen: (I should add that when I give the incorrect email address/password combination, it says simply "Username and password doesn’t match"- which is how I know that I did indeed enter the
correct information).

Sorry, this is not a valid Gmail login.
You cannot log into Gmail using your Google Account username and password.

Gmail is in a limited test period and is only available to a small number of people who are helping test and improve the service before it is made more widely available.

If you have been asked to test Gmail and have not yet created a Gmail account, please click on the link in your invitation email.

If you have been asked to test Gmail and have already created a Gmail account, please try to log in again using your Gmail username and password.

UPDATE: After setting up another email address (and multiple attempts later), one (less desirable) email address finally gives me access to gmail. Weird. Is this normal?

It’s cool. I’ve heard great things about it. I like the google search feature for finding old emails for sure though. Very nice!