How-To: Install KDE 4.3 in Ubuntu/Kubuntu 9.04 Jaunty Jackalope

KDE 4.3 was released just yesterday, and it comes with a lot of great new features and improvements, like the the new Plasma theme called Air, new Plasma widgets, several improvements to Dolphin, the default KDE4 file manager, improvements to the KDE games, and these are just a tiny part of all the improvements KDE4 introduced. The full announcement including reader's changelog can be found on the official KDE4 website, here.