My son applied to SS in Jan 2006, a week later he received a phone call from his ALO. They spent nearly a hour on the phone. One week after the phone call, he received an email that he was in. My son's friend who is the #1 in the class and had the same PSAT score got his email the next day after he submitted his application.
What my son said they told him at SS, first the will be looked at first. This would seem to be true because the applications were loaded before they went to SS. Second, 40 plus percent will be in the incoming class. Third, not everyone who went to SS will be accepted, but a high percentage will be, single biggest show stopper is medical issues.