IETF124 is happening in Montreal, Nov 1st to 7th https://www.ietf.org/meeting/124/
Attending the IETF Hackathon is free (date TBD, usually at the beginning), and we'll also plan ATProto working sessions for Private Data, and other areas of collaboration or discussion offsite from the IETF.
The location is the IETF conference venue, spaces where the community can meet are TBD.
RSVP with your email to be notified, and feel free to add notes and suggestions to the ATProto Community Forum https://discourse.atprotocol.community/t/montreal-community-gathering-private-data-sessions/43