Got an update on the Stockholm workshop via the organizers:
"This event is FREE as previously stated. However, seats are limited, so please do wait to order plane tickets and what not until we release information on how to RSVP. Also, if there are any questions regarding the event, feel free to contact me: marcus.stade at gimlet.se"
I have received word that they are putting together some sort of ticketing / RSVP system right now. I will be posting more info as it becomes available, and you can always check the original event post as I will be updating that as well.