[djbaxter]

I don't use either vBadvanced or vBSEO (except for the sitemap add-on).

However, this may help:

How to ensure that your sitemaps can be found by ANY search engine...

Discovering Sitemaps
Brent Hands, Program Manager, Live Search

When we first teamed up with Google and Yahoo to support sitemaps as an industry standard, it was with the express intention of driving the protocol forward. Making it into a simple, effective way to tell all search engines about the structure of your site.

Today, I'm happy to announce the latest addition to the protocol: Sitemap Autodiscovery. Autodiscovery gives siteowners the ability to easily share their sitemaps with all search engines at once, without the overhead of manually submitting them to each one. In order to share your sitemap with the crawlers at large, you simply provide the following line in your robots.txt file:

Sitemap: <sitemap_location>

where <sitemap_location> is the complete URL of your Sitemap Index File (or your sitemap file, if you don't have an index file). This directive is independent of the user-agent. so as long as it is present in the robots.txt file, all engines will be able to find your sitemaps. I see this as an important extension to the protocol, as it removes the need to individually submit sitemaps to each engine - simply add one line to your robots.txt file, and we will find your new and updated sitemaps automatically.

Although we aren't ready to start consuming sitemaps quite yet, I encourage you to build a sitemap and add the "sitemap" directive to your robots.txt. As soon as we roll out support (before the end of the year), we will be able to start crawling your sitemap files immediately. If you want more detail on the sitemaps protocol, including autodiscovery, check out www.sitemaps.org.

This is also endorsed by Yahoo! -

Webmasters Can Now Auto-Discover With Sitemaps

Since working with Google and Microsoft to support a single format for submission with Sitemaps, we have continued to discuss further enhancements to make it easy for webmasters to get their content to all search engines quickly.

All search crawlers recognize robots.txt, so it seemed like a good idea to use that mechanism to allow webmasters to share their Sitemaps. You agreed and encouraged us to allow robots.txt discovery of Sitemaps on our suggestion board. We took the idea to Google and Microsoft and are happy to announce today that you can now find your sitemaps in a uniform way across all participating engines. To do this, simply add the following line to your robots.txt file:

Sitemap: http://www.example.com/sitemap.xml

Please provide the complete URL for your Sitemap on this line. We will pick it up wherever you put it in your robots.txt file. This directive is not specific to user-agent. If you have multiple Sitemaps, you can point to your Sitemap index file on this line. Details about the Sitemaps protocol including this addition are available on the protocol website -- http://www.sitemaps.org.

If you prefer, you can continue to issue Sitemaps to Yahoo! Search by simply inputting the URL for your Sitemap and submitting. Or add feeds to a site you are already managing under 'My Sites' in Site Explorer. This also allows us to provide more feedback to you about what we are doing with the sitemap.

We're also happy to have some east coasters, Ask and IBM, announce their support for Sitemaps. The more the merrier!