Applying margin:0 to * will have the possibly undesired effect of removing the default margins for <blockquote>. If you are manually setting the blockquote margins, it doesn't matter.
As for the extra <div>, it's probably a (dirty) trick to allow having naked inline elements (<span>, <img>...) out of <p>s, since this is not valid in XHTML:
Code:
<body>
<p>Some text</p>
<span id="pg_2"/> <!-- span cannot a direct child to body -->
<p>Some text</p>
</body>
but this is OK:
Code:
<body>
<div>
<p>Some text</p>
<span id="pg_2"/>
<p>Some text</p>
</div>
</body>