Hello!
Sorry for my poor English, I'm from Ukraine.
As for me, now KDE4 has poor staff of 3D-effects.
For example, Compiz has effect 'Ring Switcher'. This effect is very usefull and has goodlook style for me.
Must be created section 'Additional Effects' for downloaded effects from third-party developers, similarly to widgets from kde-look.org. We can download widgets and set up its on Desktop.
In future distributive owners can select usefull additional effect and create own package for KDE.

For downloaded widgets needs additional section too. Now all downloaded widgets and widgets from Linux distributive I can see together. But downloaded themes, styles and others I can separate out.