First and foremost, with the upcoming 9.10 "Karmic Koala" release of Kubuntu, the distribution upgrades KDE to KDE 4.3, and this alpha release already contains the recently released KDE 4.3.1 bugfix release. KDE 4.3 brings many needed improvements to the KDE4 desktop. This release also comes with Plasma's new netbook-oriented interface.
Finally, Kubuntu also takes the nessecary steps to make Gtk+/GNOME applications look nice and well-integrated in a Qt/KDE environment by shipping the QtCurve engine. The Gtk+ Appearance System Settings module also makes a comeback so you get fine-grained control over the Gtk+/GNOME applications running in KDE. About time, I'd say, other KDE distributions have had this for a while.
They've also focussed quite a bit on making OpenOffice.org integrate well within a KDE environment. "Written by our very own elite Kubuntu developers, OpenOffice 3.1.1 introduces KDE integration. This means that all OpenOffice applications will look at home with the default 'Oxygen' KDE theme and use the KDE file dialog for opening and saving documents." I'm just wondering if this is a static solution or a flexible one; in other words, if you change KDE4 styles, will OpenOffice.org be changed accordingly, or will it continue to use Oxygen?
There's also some "bad" news (depends on hoe you look at it). Previous alpha releases defaulted to the webkit-based Arora browser, but alpha 5 defaults back to Konqueror. "It was decided that it's [sic] superior integration with KDE was worth more than the hassle of switching default web browsers a lot. However, Arora 0.8 will still be shipped on the DVD for those who want to [sic] Arora for it's [sic] superior performance with social web applications such as Facebook."
Kubuntu is a distribution which always felt a bit like the stepchild Canonical never really wanted to have. It could really use some love and it's good to see they are making improvements. Kubuntu 9.10 is scheduled for release October 29.