I, too, have often wished for the method attribute you describe.

That said, if you're already using javascript (as news.YC is), I really don't see why you wouldn't make use of xhr. In which case you could submit the request as a post.

Note: I haven't poked around enough to see if news.YC works without javascript. If they degrade gracefully, more power to them, and I can almost understand the decision to do it the way they have.