Basically they use your money to pay for the machines of other people already in line to get theirs (see where it says X needed to clear). These are great if you get in quick and get one ... but someone is sure to get screwed in the end and you are left with the knowledge that you contributed to that.
Generally this is highly illegal. As soon as the FTC catches on they'll shut this stuff down - unless they are already operating off-shore (speaking from a US standpoint).
Lots of people get took on the money markets for A LOT of money with trading scams like this.
Here is the most recent one I'm aware of: http://starbulletin.com/2003/12/11/news/story3.html