My new roommate is the Zeitgeist Group Coordinator in my town, I'm very much used to these arguments by now..
They will say that we don't need money, we only have money because there is scarcity of goods. They will say that scarcity is artificial because they will agree that the corporations use government power to inhibit humanity from it's potential to feed and provide better for everyone because the corporations want us to depend on them.. They will explain that the technology is already available to feed everybody and we can easily automate production of building materials and such, we just need to build better and more sustainable food systems that aren't modeled around agribusinesses like Monsanto. Large-scale aquaponics comes to mind, I heard some guy grew a million pounds of food in a year on 2 acres of land. There are plenty of people who enjoy farming enough and they would be happy to just have some equipment and land to farm on. What they are saying isn't completely out of the question, the big question is whether the person is willing to use coercion or violence to achieve what they are trying to achieve. Generally they will agree that violence and coercion are not good tools to achieve what they want, that it will have to come about as a result of humanity realizing what they are actually capable of and doing it.
I just explain that freedom takes the tool of the corporations to inhibit us away so that mankind can work towards getting rid of scarcity.
I think it is fair to admit that if scarcity didn't exist, money wouldn't hold any value and would inevitably become extinct naturally, just like what the Venus Project people want.. but to get there, we have to take away the power of force and coercion and then we can employ the technologies that they want in order to work towards getting rid of scarcity. Freedom will lead to increase in wealth of everyone, and once everybody has savings then people will actually have the ability to invest in this type of stuff.
Another lesson many of these people need to learn is Peter Schiff's father's book about the fishing island. How do you build all of this infrastructure while providing for all of the builders without taking resources from other people by force? They often don't understand why it is better to have a factory owner run a factory than someone who has no vested interest in the factory.