Howdy folks. I'm actually going to be in on the chat in question, so here's just a bit of clarification:
The applicants who were invited to the chat represent a random selection of applicants who have submitted their AMCAS application to Pritzkerthey didnt pay attention to whether you had already received an interview invitation, havent yet submitted your secondary, etc., they really want to talk to a random selection of people in all stages of the process. If you werent selected, it isnt an indicator of anythingyour name just didnt happen to have been picked. It doesn't mean that you've been rejected, that you're going to be rejected, or that Pritzker hates you. Keep in mind that there will be subsequent chats at later dates that will include random selections of applicants as well. Despite the fact that they tried to limit the amount of people that will be participating, invitations went out to about 1800 applicants, or 25-30% of the 6000+ they've received so far.
If you have already received a rejection letter, the admissions people at Pritzker are always willing to talk to rejected applicants to help them understand why they were rejected, so feel free to join in the chat if you want to.
Regarding the email info leak, it really is just a case of human errorthe office switched to a new email system and the person who sends the emails about your applications being complete didnt know how to use the bcc feature in the new email system. While they feel badly about the honest mistake, they want to assure you that no other personal information was at jeopardy beyond email addresses.
That's about all I know from talking to the admissions peeps, so if you have questions about it, email me. Again, don't worry about the secret meaning behind whether you were invited to chat -- there isn't one.
Peace. -B