When to use SECTION element?

Question

I'm a bit confused by the new HTML5 element, <section>. What is the correct way to use it?
Consider this outline:

<article>
  <header>
    <h2>Title</h2>
    <p>Spiffy tagline</p>
  </header>
  <section>
    <p>My content! BLA BLA BLA YADDA YADDA</p>
    <p>Some more content!</b>
  </section>
</article>

Does it make sense?
What if I had smaller articles, with just a title and a brief text? Would it be (semantically, spec-wise, etc.) to omit the section?

Answer 1

If you don't need sections (have small articles) you can just use a bare <article> entity around your content. And when you don't, the section can wrap sub-titles and paragraphs in those sections.

Check out the html5 section specs.

Example:

<header>
  <h1>Blog Posts</h1>
</header>
<article>
  <header>
    <h1>Article Header</h1>
    <h2>My Awesome Stuff!</h2>
  </header>
  <p>My content! BLA BLA BLA YADDA YADDA</p>
  <p>Some more content!</b>
</article>
<article>
  <header>
    <h1>Article 2 Header</h1>
    <h2>More of My Awesome Stuff!</h2>
  </header>
  <section>
    <header>
      <h1>Getting started</h1>
    </header>
    <p>Getting started text</p>
  </section>
  <section>
    <header>
      <h1>Now you're underway</h1>
    </header>
    <p>Underway text</p>
  </section>
  <section>
    <header>
      <h1>Wrapping up</h1>
    </header>
    <p>Wrapping up text</p>
  </section>
</article>

Answer 2

I think you'll find Dive Into HTML5, a book in progress, a great resource. Here's a relevant section on when and how to use new semantic elements. For your example, I think that you may be able to omit the <section> tag.