What is MetaFilter Projects?
MetaFilter Projects is a place for members of the site to announce their latest web projects with the rest of the membership. Members can vote and comment on your project and may repost it to MetaFilter proper if a member deems it interesting enough to promote to the main site.
Is this limited to sites? Can I link to a particularly witty blog post I made?
I'm limiting the ability to post a project of yours to once every 30 days, and the thinking behind that is that the projects you choose to announce should be significant works—the types of things that typically take a few months to design, create, and build. Essays or blog posts aren't really what it's about here. We're talking larger stuff, like whole sites.
What kind of feedback can I get from a post here?
The rationale behind that is the projects page (much like the old projects email list) is merely a springboard for posts to the main MetaFilter site, if a member decides it's a project worth sharing there. The votes are an indicator of how much the membership likes your project, in the off chance it doesn't become a post, you'll at least know if it struck a chord with anyone.