Im not sure if this has been posted yet, but I wanted to pass the rewrite rules for those using IIS7+ as this plugin doesn't seem to generate them itself.
<rule name="Google Xml Sitemap 1" stopProcessing="true">
<match url="^sitemap-?([a-zA-Z0-9\-_]+)?\.xml$" ignoreCase="true"/>
<action type="Rewrite" url="index.php?xml_sitemap=params={R:1}" appendQueryString="false"/>
</rule>
<rule name="Google Xml Sitemap 2" stopProcessing="true">
<match url="^sitemap-?([a-zA-Z0-9\-_]+)?\.xml\.gz$" ignoreCase="true"/>
<action type="Rewrite" url="index.php?xml_sitemap=params={R:1};zip=true" appendQueryString="false"/>
</rule>
<rule name="Google Xml Sitemap 3" stopProcessing="true">
<match url="^sitemap-?([a-zA-Z0-9\-_]+)?\.html$" ignoreCase="true"/>
<action type="Rewrite" url="index.php?xml_sitemap=params={R:1};html=true" appendQueryString="false"/>
</rule>
<rule name="Google Xml Sitemap 4" stopProcessing="true">
<match url="^sitemap-?([a-zA-Z0-9\-_]+)?\.html.gz$" ignoreCase="true"/>
<action type="Rewrite" url="index.php?xml_sitemap=params={R:1};html=true;zip=true" appendQueryString="false"/>
</rule>