The XUI branch of this project is now available for download from the releases page.

http://sourceforge.net/project/showfiles.php?group_id=187008&package_id=238728

Features:
* New WPF-based UI
* Dynamically resizeable thumbnails
* Thumbnail information
* Sort by Name, Size or Source
* Filter results under or over a specified size, or by maximum results for each source
* Substitution syntax path to save images
* Local files search that matches save pattern
* Enable or disable scripts from the command line
* New strongly typed interface-based script model; write compiled scripts in any .net language
* Backwards compatible with existing scripts
* Backwards compatible with existing command line parameters, including old CoverDownloader parameters.
* Analyse files to find Artists and Albums from tags, and check if album art is already present.... read more

We just released Album Art Downloader 0.5 final.