JimmyC: Invites for the last beta weekend were only sent to people who ordered before 11.11.11.
You get early access for pre-ordering anytime I believe, but depending on when you pre-ordered, you'll get up to 5 days early access.
Invites for beta testing go to anyone who signed up for testing before 11/11. If you didn't you were able to get an invite from many of the fansites.
Also you can go to http://www.swtor.com/tester and confirm for the test if you somehow missed out on an email invite.