I'm running KDE 4.2 on Fedora 10 and it works without problems. Like KDE developers said the first two versions were for "developers". I think those version should have been numbered differently though.
The problem with desktop OS'es is the future is
no long Windows v Linux. Obviously there is the Mac but machines booting straight into Vmware applications or straight into browsers that have just enough OS to support there function are here.
What this means is that the traditional desktop OS supports generic computer use, but users are moving increasingly towards specific computer use. Take for example Games, the PC is no longer the platform of choice. Citrix, VDI, AJAX, Silverlight, Flash etc
are increasingly delivering richer clients and content. Even the humble PC is under attack, take for example my company, we give everyone a thin-client device that just has enough brains to run the Citrix ICA Client.
There will be a hugh market for generic computer use, but the percentage will not be as large as it once was. People won't care if it's Windows or Linux for that matter so will be a hollow victory if it is the latter.
People see buttons they can click on with the mouse and text boxes they can put stuff in that all helps them do whatever they want to do. What is happening underneath isn't important, it really isn't. We in IT have to realise this, the popularity of the Asus
EEE and the start of NetBooks proved this. No one really cares about Windows ... or Linux ... or Mac ... or Flash .... or Ajax ... because they haven't got enough emotion invested in the choices.
The only people that do care are the ones that have invested a career in it ... but ultimately at the end of the day we are just service providers.