I would second this.

In my mind, however, what would be more useful for us budding founders is a place where we can share our ideas and projects in their early embarrassing states. It would be nice the be able to get feedback right at the beginning when I have only the the vaguest idea, and then to be guided by feedback as the project develops and matures. I would not be comfortable to share my pre-pre alpha project on reddit. And people would not be interested.

I believe that the search-space is too great that we should ever worry about other people stealing our precious idea. Starting from one point, different people would diverge and develop in different ways.

I don't know. But I would really welcome more openness. I think when an idea is interesting, and new, people would rather cooperate, and help along. Competition only happens (I hope) when people are chasing after the roughly same fad.

Why not submit a blog post the normal way? Is this a separate kind of post?

Well, people tend to dislike it if you submit your own blog posts (you're biased, too wordy, trumpeting your own horn, etc.). So this would be a place to hold virtual design reviews: ask people to look and provide objective feedback; the comments thread would function as the Q&A part between the hacker and the community of reviewers.

wouldn't it be simpler to just decide that it's ok to submit your own posts? some people have done that already and it seems fine to me: they're among the best links here.

Probably they dislike the content and not the posting itself.