Starting from April 19th the new People Mover (Cable Car) starts service between Tronchetto main car&tourist bus terminal and Piazzale Roma Venice's main gateway.
In only 7 minutes after you've dropped your car you can reach the city's main transportation hub. Service is open daily from 7am to 11pm at the cost of one euro per way.
Though the intermediate Cruise Terminal stop is not open yet, it will in months.
See this youtube movie showing the inauguration of the service and how does it work.
More information: www.youtube.com/watch?v=8Wo2EK-xFZ0