Message boards: every activity now has a board where the people who've joined can coordinate. New notifications: know when someone bails, when a friend request is accepted, and when your activities get new messages. Redesigned time picker and a smoother activity-creation flow. Activity cards now show spots remaining at a glance. Polished onboarding, plus an easy way to turn on notifications later if you skipped them. Bug fixes, including one where re-editing an activity showed a blank form.