Dreamwidth is now in open Beta. Open, as in more people can join and invite codes are easier to come by.
If you set and confirmed your email on your OpenID account before open beta opened OR if you were a member of one of the mailing lists, you'll be getting an invite from dreamwidth itself once they have a chance. Some people have already been promised invite codes from existing members.
If you're not yet a member and you're not in one of the above three categories and you still wish to join, then you'll need an invite code from elsewhere.
Comments screened for the moment, will probably be unscreened later.