How do I rename a domain and preserve SEO?

Check out Google's guide to moving a site:

• Use a 301 Redirect to permanently redirect all pages on your old site to your new site.
• Check both external and internal links to pages on your site and make sure they are updated to point to the new domain (obviously, for external links this is difficult)
• Use the Change of Address tool in Webmaster Tools to notify Google of your site's move.
• We recommend that you create and submit a Sitemap listing the URLs on your new site.

After the move, sanity checks to make sure things are working:

• Check the web crawl errors for both your old and new sites, to make sure that the 301 redirects from the old site are working properly, and that the new site isn't showing unwanted 404 errors.
• If you've submitted a Sitemap, the Sitemap Details page lets you see how many URLs in your Sitemap we've crawled and indexed.

Esp. the Change of Address tool might be of interest.

I didn't read the link above, but no doubt that http 301 "permanent" redirects will be important to preserving both bookmarks and search ranking.

I'm sure this is covered in the google doc that jmb referenced, but:

• Tell google your site has moved using Google Webmaster Central
• Set something up on the old site to return a 301 redirect for EVERY individual url on the old site to the corresponding url on the new site, I imagine this would be some effort but would probably also be the most effective