One of the most popular podcasting plugins for WordPress, I have also used this to run my podcast on Mad Lemmings.
It is relatively easy to set up, although I would personally follow a tutorial to make sure you get it right. This is why, although I have not yet tried it, the Serious Simple Podcasting plugin looks simpler and in many ways more powerful. Check that out too.
The main power of such a plugin is getting your RSS feed set up so you can pass that (ie inform) to places like iTunes and Stitcher.
The plugin also gives you a panel to fill in on each post that enables you to hook in your media file (from Libsyn, Soundcloud etc) and turn your blog post into a podcast episode.
They also give you a shortcode to add to your page to position a podcast player, which is actually pretty good. Although there is a better player around developed by Pat Flynn if you can get hold of it.