Can WordPress Read Its Own RSS Feed?

Better to use a query loop to show posts, which is a modifed version of the main WP loop. This query loop won’t interfere with the main WP loop and can be used mutiple times in a sidebar or post/page with php execution enabled. Use a php widget in your sidebar: WordPress › PHP Code Widget « WordPress Plugins

Change mycategory to the name of a category, or remove to show all. And change showposts to the number of posts you want, or -1 to show all. You will have to CSS style the output.

<?php $my_query = new WP_Query('category_name=mycategory&showposts=1'); ?>

<?php while ($my_query->have_posts()) : $my_query->the_post(); ?>

<a href="https://wordpress.stackexchange.com/questions/8168/<?php the_permalink() ?>" title="<?php the_title(); ?>">

<?php the_title(); ?></a>

<?php the_excerpt(); ?>

<?php endwhile; ?>

Also see The Loop « WordPress Codex and Function Reference/WP Query « WordPress Codex