The first public release of event-osd, a notification system for the WDTV’s GUI, is out. It enables third party scripts to modify the GUI on the fly based on the current directory.
This release is designed for the WDTV firmware in the version 1.02.07 it probably only works with this exact version or other firmwares like ext3-boot or WDLXTV that are based on the 1.02.07 too.
You can download it from http://sourceforge.net/project/downloading.php?group_id=261153&filename=event-osd-r100-wdtv.zip.
A, very short, documentation for developers is available at the Wiki at http://sourceforge.net/apps/trac/wdtvtools/wiki/event-osd.
A video showing event-osd in action with appletrailerfs: