GPG is a gimmick? What, you can crack encrypted messages now?
No. GPG is very useful for some applications.
It is completely unnecessary for a trust system and a stock exchange.
Why do you think no real stock exchanges use gpg?
What problem is it solving?
You never know, it might all change one day. the same way bitcoin is going to change the financial world, PGP could be a useful tool for it in the future too. What's with this pretention of knowing what will or wont be a success? They guy is experimenting a new kind of exchange, let him be, it's worth the experience I think.
You're right pgp could be useful in the future but as of now everyone seems to be doing fine without it.
You miss the point of PGP / GPG. First: it probably won't be useful in the future, cryptography moves and advances. Nonetheless, GPG as it is used today is NOT use primarily as a means of encryption. There are plenty of tools that are more performant, more efficient, and arguably more cryptographically secure. GPG's primary purpose is a means of confirming one's identity.
A similar role is served by sites employing DNSSEC to confirm the validity of an A record: it is a means of confirming that that (barring some sort of exceptionally advanced or esoteric attack) you are indeed talking to the server for whatever.domain.you.specified.com. It's a way of confirming the identity for that FQDN.
Traditional stock exchanges, such as the NYSE, have evolved from ancient analog systems, so a lot of this infrastructure (whereby the authenticity of orders is confirmed) is based on the equipment of those brokerages / seat holders being close to the NYSE's tin. An exchange such as MPEX is not evolving from pen-and-paper, so it has instead chosen to take advantage of the system that is one of the most secure and renowned for identity verification over the Internet. It's not perfect, it has nuances and failings of its own, but it's just as cryptographically sound as the NYSE's "please put your box next to ours and run a fibre cable into the jack at the back" solution.
PS. You seem to be a fan of hyperbole, especially with your NYSE comparison. Ironically you fail to take the effect of time into your puerile vitriol. By comparison: if a competitor to Facebook sprung up 2 years ago, would it have 1.32 billion active monthly users by now? Historicity leads to a network effect which creates the companies and organisations we know today. Comparing an organisation with nearly 2 centuries of history with one that has been around for only a few is silly and beyond idiotic, especially since the global paradigms they are operating within are so vastly different. I used to think you were more intelligent than you have proven yourself to be, Jimbo.