I was at VMware Partner Xchange in San Diego. I talked to a number of VMware badged employees. As for the VCDX, VMware is not planning to make money on the exam. They had to write their own test engines for both exams from scratch. As for the review board, initially the panel will consist of VMware PSO's. After that, any of us who have passed the entire track, will sit on the board where people will have to defend their design to us. There are over 20000 VCP's worldwide, however they do not expect more than 100 (one hundred) VCDX worldwide. It will be expensive due to travel costs, but that will be about it.
I do know that they are toying with the idea of interim certs, but that is still in discussion.
RickWininger