blockquotes and divs can be styled to look identical - the difference is almost pure semantics. The only big difference is that you can set the "cite" attribute within the blockquote tag, divs you don't.
If you change the css from Jelby's example above to this it will look identical.
Code:
blockquote.poetry {
margin: 1em 0 1em 2em;
}
blockquote.poetry p {
margin: 0;
padding-left: 3em;
text-indent: -3em;
text-align: left;
}
blockquote.poetry p.indented {
margin-left: 2em;
}
blockquote.poetry p.first {
margin-top: 1em;
}
Like phillipgessert, I would use a div for poetry unless it was part of a longer quote - then semantically blockquote would be more correct.