Change to KDE 4 by default in Kubuntu Intrepid and use KDE 4 applications where they are sufficiently stable.
Kubuntu 8.10 is based on the cutting edge KDE 4 desktop.
KDE 3 is obsolete and largely unmaintained. Keeping with KDE 3 would offer no advantage over giving users Hardy.
In hardy we renamed KDE 4 packages with a -kde4 suffix, changed the install path and changed the configuration directory. For Intrepid this will be dropped for KDE desktop packages so the KDE 3 packages will become KDE 4. These packages will be in main and a number of new build-dependencies will need main inclusion reports.
KDE 3 and KDE 4 libraries can exist side by side so where there is no stable KDE 4 application, we can keep the KDE 3 application. The KDE 3 kdebase module will be replaced by KDE 4 so applications which depend on this, K3b, Amarok, Digikam and KMail will need to be compiled without kcontrol support if there are any cases where we keep the KDE 3 version.
We will review KDE 4 ports of applications for suitability for inclusion at the time of KDE 4.1 release and before feature freeze. Applications we are still unsure about the quality of the KDE 4 port include Kontact, Digikam, Amarok, Kopete and Ark. If the KDE 4 version can work without regression and with successful upgrade, we will use it.
We will keep an eye on kdewebkit for use in Konqueror, it currently has problems with native widget rendering but if that is solved before feature freeze we will consider changing to it.
We will turn on kwin's compositing by default, using the same blacklist as compiz to test if the graphics setup is suitable.
Because this is a major upgrade, and there will still be rough edges in KDE 4 we will not prompt the user for upgrade to Intrepid from Hardy when it is released, this follows what Ubuntu Desktop will do. Our marketing will follow that this release is an upgrade for those who want the latest new release, but may not be suitable for those who do not want to put up with some rough edges.
We will need to implement .pot file generation for KDE packages to integrate KDE 4 with Launchpad Translations. The script for this is just an updated version of the one we use currently with KDE 3.
In Hardy KDE 4 data and settings were entirely separate from KDE 3. In Intrepid they will be moved to ~/.kde, making it upgrade from KDE 3 (and ignoring any KDE 4 settings used in Hardy). There have been no reports of problems with KDE 3 to KDE 4 upgrades (notably Fedora 9 did settings upgrades and have not had any problems), but we will write test cases and get the community to check that it works reliably for them before release.