I was emailing with them a bit about a year ago about this. They are geared towards members basicly, so you either have to become a member or find a member to deal with.
They do have their own brokers, so you can actually call in and have them handle orders - I don't really know how well that works though, or how payment/clearing is handled.
I think the exchange has some very promising opportunities, but it doesn't seem like there are any members targeting even professional traders.