Patrick Volkerding (Slackware Project Lead) gives glowing thumbs up to KDE4 and slates it for inclusion into Slackware 14. Slackware is currently at version 12 and releases once a year. At this rate, KDE4 will be in Slackware in 2009. Among other things, Patrick says the following.
The look of the new [KDE] desktop is stunning, and the use of SVG and hardware acceleration gives (IMHO) even something like MacOS a run for its money in terms of appearance and user-friendliness. We look forward with great anticipation to merging KDE4 when it is mature enough (and it's getting there fast), and then watching it just get better and better.The full quote can be found in Slackware ChangeLog.