Well the software is free, you can download and run it on your own server (Express) or you can have it run via your Amazon EC2 account (Flex), which is not free. So while the software is free, the computer time is not (although I think will pay for your first 30 Amazon EC2 hours to try it out).
What about the "Laundry Basket"? I'm never really taking things out of the trash, but in the morning you sure as hell can see me searching through the laundry basket to find that shirt that always seems to disappear.
I always wondered what would happen if I searched for a domain name and then before I finished the checkout, the name was no longer available. I mean I guess it is probably not that likely, but it is certainly not impossible. This way, if you search for a domain name, NSI pre-registers it so that when you goto buy it you can be assured that no one else will have purchased it already.