Google has decided to follow MSN’s lead and allow webmasters more control of the ODP site titles and description snippet displayed in their search results.
Google’s creation of sites’ titles and descriptions (or “snippets”) is completely automated and takes into account both the content of a page as well as references to it that appear on the web. While we’re unable to manually change titles or snippets for individual sites, please be assured that we’re always working to make them as relevant as possible. One source we use to generate snippets is the Open Directory Project. You can direct us not to use this as a source by adding a meta tag to your pages.
To prevent all search engines (that support the meta tag) from using this information for the page’s description, use the following:
META NAME="ROBOTS" CONTENT="NOODP"
To specifically prevent Google from using this information for a page’s description, use the following:
META NAME="GOOGLEBOT" CONTENT="NOODP"
If you use the robots meta tag for other directives, you can combine those. For instance:
META NAME="GOOGLEBOT" CONTENT="NOODP, NOFOLLOW"
Note that once you add this meta tag to your pages, it may take some time for changes to your snippets to appear in the index.
More information is available in Google’s Webmaster Help Center and in the Google Sitemaps Blog