For Debian/Ubuntu we are working on packages which will eventually be uploaded. The wnpp bug reports can be found here:
Songbird is a free iTunes-like music player with integrated library functions and is based on xulrunner library. Like Firefox the functionality can be extended with AddOns. These AddOns include skins and plugins to fetch covers etc. Device support for the Apple iPod is implemented as an addon as well, it can be found here:
The source code for the iPod has been published and might provide a good starting point in order to write a Songbird plugin for HiMD/NetMD-support based on our sources:
The standard media player by the KDE project is called http://amarok.kde.org/amarok. Similar to Songbird, someone might write a plug-in using libhimd which allows to download or upload tracks to/from the MiniDisc Walkman within amarok without additional software. We are looking for amarok developers with expertise regarding such plugins.
Please see also this thread: http://mail.kde.org/pipermail/amarok/2009-April/030130.html