Your default WordPress installation has a problem.  Your posts slowly get pushed into "pagination death" as they age; your older trusty content gets buried deeper and deeper internally.  Furthermore, duplicate content issues plague your category and main listing pages.

Slowly, but surely, every old post in your WordPress blog gets buried under 50 pages of other posts.  Slowly, but surely, all of the duplicate content adds up.

I saw this post on Digg.com today, and although it has merit, it doesn't dive into gory technical details like I will here.  There are really only 2 or 3 things you have to do to improve the SE-friendliness of WordPress substantially:

1. Change the pagination to look like this:

I demonstrate how to do for WordPress step-by-step in this post with a simple plugin and a few bits of code.  This keeps the posts less-buried within your blog's link-structure.  Check it out.

2. Eliminate most of the duplicate content:
This is tougher.  Let's talk about duplicate content for a moment.  Ideally, content would only appear at one URL to avoid duplicate content in every case.  This is not really possible, so let's be realistic.

The logic I will suggest is that one should show the full content only on the actual permalink page (the post's page), and the home page for the most recent posts.  All other pages will only show titles and excepts.  To do this, you must modify your wordpress template in "/wp-content/themes/{your-theme}/index.php."  The modification will look something like this:

<? if (is_home() && (!$paged || $paged == 1) || is_search() || is_single() || is_page()): ?>

<div class="entry">
                
<?php the_content() ?>

<? else: ?>
                
<small>Archived; click post to view.<br>
<b>Excerpt:</b> <?= substr(strip_tags($post->post_content), 0, 300); ?> ... </small>
                
<? endif; ?>

It basically says what I said above, just using PHP.  Doing these 2 things will help your site get indexed properly. 

Lastly, you should probably also do the obvious, and create a site map page.  I guess that isn't a hack at all, but I recommend the following plugin:

http://www.dagondesign.com/articles/sitemap-generator-plugin-for-wordpress/

Kudos to Dagon Design for such a great plugin that I didn't have to write.  You could also create a Google and Yahoo site map, but I don't regard that as strictly necessary.

So get crackin'.  Leave a comment if you have questions.