Apparently, there are two versions that Amarok can use of libgpod4: one with GTK, and one without. I guess that if you install the package libgpod4, and then gnome, that should work. But that should be handled more nicely, would you mind filing a bug against that package?
But about the true causes of the present bug, I don't really know. Please try to run 'sudo update-desktop-database /usr/share/applications/' before you try installing GNOME - but it would be strange that KDE is not doing so already.
Apparently, there are two versions that Amarok can use of libgpod4: one with GTK, and one without. I guess that if you install the package libgpod4, and then gnome, that should work. But that should be handled more nicely, would you mind filing a bug against that package?
But about the true causes of the present bug, I don't really know. Please try to run 'sudo update- desktop- database /usr/share/ applications/ ' before you try installing GNOME - but it would be strange that KDE is not doing so already.