Summary: Configurable context menus for taskbar menu items
Example: Right mouse button context menu in K menu could offer 'Uninstall', 'Find similar' and 'Upgrade' options.
The distro maker could then for instance configure the 'Uninstall' button to do some apt-get magic, 'Find similar' would search the package database for similar programs (based on the metadata [e.g. Text editor] provided with the menu item).
Other context menu items could be added of course, but those seem to be the intuitive ones, being that the K menu offers programs. Other menus could have something different, but the good thing is that KDE just needs to offer the possibility to do it and it's up to the user/distro developer to come up with the actual ideas what to do.