This is a really interesting idea, but I'd like to see more examples with some actual data. For example, how many people check the box? Of those, how many actually sign up when the service is available?
Another good example is a guy I met who started a business putting pro sports logos on car seats. First he went to the national retail chains and got them to order a hundred thousand units. Then once he made the sale he used it to get the rights from the sports leagues to use their logos. Only then did he go out and find a manufacturer, and by then he was already guaranteed to make money on the deal. So his only startup costs were a couple weeks making phone calls, and he made a ton of money.
Because I plan to use it with my customers I knew I wanted to pay for a supported SaaS/hosted version. I have been surprised that we have been unable to have any meaningful discussion about it. I know that one interested user doesn't constitute a market, but I was dismayed with the lack of meaningful engagement beyond we will notify you when it's ready.
I think the part that's was left out of the Venture Hacks article was when someone tells you they want to buy it, have a conversation with them to understand how they plan to use it and how they value it (what are the alternatives that they are comparing it against).