Which do you think is most appropriate?

With H2 headers in list items:
Code:
<h1>Electronics Articles</h1>
<ul>
    <li>
        <h2>Article Title 1</h2>
        <p>Posted June 1, 2009</p>
    </li>
    <li>
        <h2>Article Title 2</h2>
        <p>Posted June 1, 2009</p>
    </li>
</ul>
No H2 headers in list items:
Code:
<h1>Electronics Articles</h1>
<ul>
    <li>
        Article Title 1
        <span>Posted June 1, 2009</span>
    </li>
    <li>
        Article Title 2
        <span>Posted June 1, 2009</span>
    </li>
</ul>
As a defintion list:
Code:
<h1>Electronics Articles</h1>
<dl>
    <dt>Article Title 1</dt>
    <dd>Posted June 1, 2009</dd>
    
    <dt>Article Title 2</dt>
    <dd>Posted June 1, 2009</dd>
</dl>