I have seen some sitemaps that include the home page, eg
http://example.com and others that do not.
Is including a home page of any use and recommended in any reputable documentation?
Edit: The offical sitemap site http://www.sitemaps.org/protocol.html shows examples of customization to the homepage, so the real question is if a homepage with default settings is assumed by the search engines and is only required for customization. There are defaults for the optional parameters and some people suggest leaving it to the search engine algorithm if you don't know what you are doing.
This article suggests, "By default, when you submit a sitemap to the search engines your homepage gets a priority level of 1, and all other pages get a priority level of .5", but is the only reference I have found. However, it is ambiguous and does not answer my curiosity.