KDE version 4.0.1 has been released and available for download. KDE 4.0.1 is a maintenance release for version 4.0, which provides corrections of problems reported by users. From the announcement page:

The KDE Community today announced the immediate availability of KDE 4.0.1, the first bugfix and maintenance release for the latest generation of the most advanced and powerful free desktop. KDE 4.0.1 ships with a basic desktop and many other packages like administration, network, education, utilities, multimedia, games, artwork, web development and more. KDE’s award-winning tools and applications are available in almost 50 languages.

=> KDE 4.0.1 Release Announcement