It's just a dumb communications buss for us. It's replaced most of our ETL needs with Realtime events. If an order is placed online an event is raised. Our accounting system can consume that event to create the sales order. Then the production system consume the same event to add the job to the next production batch. Each production step produces events that can be used to update other systems, including Realtime updates on the ecommerce system.
We use Jetstream so consumers don't need to be awake when producers create events.
This system spans the cloud and 3 physical locations. But, to the consumers and producers it's one buss that they only have to authenticate with once.