By default, Jetpack’s new Sitemaps module supports Posts and Pages. It also supports Jetpack’s Custom Content Types if you use them on your site.

If you’d like to add support for another Custom Post Type, you can use the jetpack_sitemap_post_types filter, like so:

function jeherve_add_cpt_sitemaps( $post_types ) {
	$post_types[] = 'your_post_type';
	return $post_types;
}
add_filter( 'jetpack_sitemap_post_types', 'jeherve_add_cpt_sitemaps' );