Aiven customers can now connect their VPCs to AWS Transit Gateway, simplifying the management of complex private network architectures. This feature allows users to reduce private network complexity by connecting VPCs through a centralized hub and spoke architecture instead of a disordered mesh network. It also enables peering VPCs across different cloud providers or on-premise environments. To set up this connection, users can follow a simple 6-step tutorial using the Aiven CLI. By utilizing AWS Transit Gateway with their Aiven project VPCs, customers can streamline and control their private network architecture more effectively.