Thanks for the cool package.

I modified the razor to filter by template. It could be tweaked to do doc types instead if you want.

@using umbraco.cms.businesslogic.template
@{ 
var templatesNotToRender = new[]
                            {
                                Template.GetByAlias("Non Page").Id
                            }; 
}

@ListChildNodes(Model.AncestorOrSelf(1), templatesNotToRender)

@helper ListChildNodes(dynamic startNode,int[] templatesNotToRender)
{

    Response.ContentType = "text/xml";
    const int maxLevelForSiteMap = 100;

    foreach (var node in startNode.Children
        .Where("HasAccess")
        .Where("!IsProtected")
        .Where("umbracoNaviHide == false")
      )
    {     
        if(node.template > 0 &&  ! templatesNotToRender.Contains((int)node.template)) {
            <url>
                <loc>@GetUrlWithDomainPrefix(node.Url)</loc>
                <lastmod>@(string.Format("{0:s}+00:00", node.UpdateDate))</lastmod>
                @if (node.SearchEngineSitemapChangeFreq.ToString() != "")
                {
                    <changefreq>@node.SearchEngineSitemapChangeFreq</changefreq>
                }
                @if (node.SearchEngineSitemapPriority.ToString() != "")
                {
                    <priority>@node.SearchEngineSitemapPriority</priority>
                }
            </url>
        }

        if (node.Level <= maxLevelForSiteMap && node.ChildrenAsList.Count > 0)
        {
            @ListChildNodes(node, templatesNotToRender)
        } 
    }
}

@functions {
    private static string GetUrlWithDomainPrefix(string url) {
        if (url.StartsWith("/"))
          url = url.Substring(1);

        var domainPrefix = string.Format("http://{0}/", HttpContext.Current.Request.ServerVariables["HTTP_HOST"]);

        if (url.StartsWith(domainPrefix))
            return url;
        else
            return domainPrefix + url;
    }
}