Best of luck to you tomorrow.
Keep in mind that you are probably one of several being interviewed on a second round, so that you might not hear anything tomorrow. If you are the first in the seconds round of interviews, it could be a week before you hear back. When I've been involved in hiring, it was always a team decision where we had to agree and then once the decision was made, the whole pay issue got decided and we completed paperwork. Even in small companies, all the i's were dotted and t's were crossed to make sure that no hiring discrimination claims could be raised.
Its great news that you've got the second interview and I don't want you to feel down tomorrow if you don't hear back right after the interview.
Job offer, job offer, job offer. I'm chanting for you, Rickki!