I get out of the loop for a day and look what I miss! This is a great MOC, and I'll have to spend time looking at it in detail before commenting. I had actually started an article on him for the front page, which I had to retool to reflect this new creation. I had put together this collage to use with the article:
Anyway, I'll scoop myself and post the breaking news here:
The mysterious marakoeschtra is a Dutch AFOL named Martin Jaspers. He's built with LEGO since he was a kid, but only recently got into castle. All of these creations were created over the last several months. He has no website other than the Brickshelf gallery and he has relatively recently joined the Lowlug forum, but is not a member of any other LUG or on-line LEGO group.