Follow the instructions at the link below to install KDE 4 for Ubuntu:

http://kubuntu.org/announcements/kde-4.0.php

Screenshots follow! 🙂

KDE 4’s Show Desktop Grid, use Ctrl-F8:

Pick running app, use Ctrl-F10

If you want some more screenshots let me know.

Update: To install extra goodies do the following:

sudo aptitude install kde4