KDE 3 features missing in KDE4
Automount of USB devices
In KDE 3 you could choose to have usb devices mounted automatically upon plugin. In KDE4.1 this is no longer possible.
Workaround: Use an automount mechanism outside of KDE4, e.g. manually edit hal configuration files and/or add the devices to /etc/fstab.
Kicker in KDE3 used to have an option to autohide. In KDE4.1 this is currently not possible.
Workaround: None. Implementation planned in KDE4.2