The latest KDE 4.2.4 is released with much improved features and lots of bug fixes. Some of the new features include a highly improved pdf reader, Okular and and a much versatile KMail. Improved applets,  efficient and smooth window management,  breathtaking desktop effects, etc are some of the highlights of KDE 4.2. The latest release in the series, KDE 4.2.4 is probably the last release before the official release of KDE 4.3, which is going to happen some time in the month of July/August. Here is How you can update your Ubuntu/Kubuntu with the latest KDE 4.2.4.