Recent posts shortcode example. Inspired by Bill Erickson's excellent Display Posts shortcode.

featured-posts.php

<?php
add_shortcode( 'infom-feature', 'infom_featured_items_shortcode' );

function infom_featured_items_shortcode( $atts ) {
  extract(shortcode_atts(array(
		'post_type' 		=>	'page',
		'id'				=>	false,
		'include_excerpt'     	=>	false,
		'image_size'          	=>	false,
		'posts_per_page'		=>	3,
		'read_more'			=>	false
	), $atts));

	$post_type = sanitize_text_field( $post_type );
	$read_more = sanitize_text_field( $read_more );
	$include_excerpt = (bool)$include_excerpt;	
	$image_size = sanitize_key( $image_size );
	$posts_per_page = intval( $posts_per_page );
	
	$args = array (
		'post_type'			=>	explode( ',', $post_type ),
		'posts_per_page'		=>	$posts_per_page
	);
	
	if( $id ) {
		$posts_in = array_map( 'intval', explode( ',', $id ) );
		$args['post__in'] = $posts_in;
	}
	
	$krogsquery = new WP_Query( $args );
	
	if ( $krogsquery->have_posts() ) {
	
		$output = '<div class="featured-posts">';
		
		while ( $krogsquery->have_posts() ) {
			
			$krogsquery->the_post();
			
			$output .= '<h3><a href="' . get_permalink() . '">' . get_the_title() . '</a></h3>';	
			
			if ( $image_size && has_post_thumbnail() )  
				$output .= '<a class="image" href="' . get_permalink() . '">' . get_the_post_thumbnail( get_the_ID(), $image_size ) . '</a> ';

			if ( $include_excerpt ) 
				$output .= ' <div class="excerpt">' . wpautop( get_the_excerpt() ) . '</div>';
				
			if ( $read_more )
				$output .= '<a class="read-more button" href="' . get_permalink() . '">' . $read_more . '</a>';
	
		}
		
		$output .= '</div>';
	
	}
	
	wp_reset_postdata();
     
     return $output;
}

?>