Following the pseudo-reveal of Jonathan Blow's next "philosophical, and quiet" puzzle-exploration title, we contacted the cerebral developer to see what details we could discern about the project. He responded, and explained that he got the idea for the game a few months before the launch of Braid, but developed some trepidation about tackling "a more-expensive, harder-to-make 3D game." During those doubt-filled days, he worked on the prototype projects (such as the 2D RPG) we heard about.
A few weeks ago, he began "working on the game in earnest," and is now hiring 3D artists to help realize his vision. He assumes it will be another downloadable title, but isn't sure -- it's not set to drop for two years if his team stays on schedule, and who knows what platforms will be around then? Blow said we should hear more concrete details about the title as his team begins to produce some concept art and in-game visuals. We'd suggest keeping an eye on his blog 'til then.