D4rkShaDoWz
Super Freak
It's a little hard to be certain just yet.
Based on the picture from the show, there's definitely an elbow joint. Current theory is HT's evolving their use of muscle bodies and have deveolped a new body that usese muscle features wherever possible while still using joints where necessary, so the overall will look better but posability won't be totally lost.
I think it's just a solid plastic body with the pieces sculpted to shape muscles rather than part rubber muscles and part normal plastic, but we won't know for sure until official images surface or sharp photos of the image at the con display show up.
That's what I think as well. I'm sure this will be shown at SDCC at the Sideshow booth so hopefully we can get a better view of the fig. It's odd that they haven't posted any pics of it on their site since MJ Thriller is there.