This plugin uses the Last.fm API to pull your Last.fm info and caches it for quicker processing later. An earlier version pulled the XML every time, so the new version is much quicker.
The HTML generated by this widget for your sidebar isn't the prettiest, but there is apparently some work being done for skins. Personally, I simply went into the plugin editor and added some markup around what was already there; it was pretty straightforward. The code in the latest version of the plugin is much simpler than the previous version I had, due to the use of the Last.fm API instead of XML, making for another savings on time when the cached data needs to be updated.
If you want to see my modified version of the plugin in action, visit http://eposic.org/music/.