This is rather strange, but I just upgraded to Kubuntu 9.10 (Karmic Koala).
Upon reboot, I had a nice play around with KDE 4.3, very nice *grins*. And it feels much swifter, as well, particularly the compositing features.
One weird quirk - Ctrl-W doesn't seem to work anymore in Firefox/Chromium etc.? It should normally close the tab, but seems to do nothing on this side. Ctrl-T, Ctrl-Pageup/Pagedown still work.
I could have sworn it worked before the upgrade. Is this a known issue or something, or is there something I should check on my end?
Also, I didn't notice the Air Plasma theme, which I'd heard so much about, so I downloaded a copy from SVN (svn checkout svn://anonsvn.kde.org/home/kde/trunk/playground/base/plasma/desktoptheme/air), and put it in the desktoptheme folder. It works, but it feels a bit hackish.
That all works fine - but is there a recommended way of getting the Air plasma theme?
Also, finally, when I start new apps, they get thrown to the left side of the taskbar - I assume that's the new behaviour, right? Is there a configuration option to change this, in case I want to? The KDE menu also seems to have moved to the right - I'm guessing there's some usability logic behind this?