KDE4Daily is an attempt to lower the barrier to entry for people who would like to test KDE trunk in the run-up to 4.2, consisting of a Qemu VM image containing a Kubuntu 8.10 base and a comprehensive set of a self-compiled KDE4 modules from KDE trunk (all at r888587, initially), along with an updater system inside the VM itself. After an unusually rocky round of development, it is time to (finally!) announce the release of KDE4Daily 4.2!
The updater downloads and installs binary updates provided by me to the full set of modules: these updates tend to be roughly 20-50MB each (although they will occasionally be larger), take a few minutes to apply, and will hopefully be pushed out daily - hence the name.
Because Qemu is distro-agnostic, you do not need to worry about distros or libraries or dependencies or suchlike; in fact, you can even test out KDE 4 while running Windows! The downside is that eye-candy such as KWin's new Composite-based effects will not be testable as Qemu does not support hardware graphics acceleration, and everything will generally feel a lot more sluggish than is the case with a native install.
KDE4Daily comes with its own backtrace-generation system so hopefully devs can be assured of having useful backtraces in any crash bugs you file, courtesy of DrKonqui. Do note that this system is still rather slow and resource-intensive, so if you do somehow manage to crash a KDE app, please be patient while the valuable backtrace is created!
This time around I have included a chunk of the kdebindings module, so you should have everything you need to start writing Plasmoids (or other kinds of KDE apps) in Ruby and Python.
An extensive FAQ is provided at the KDE4Daily homepage, above; please feel free to ask any further questions in the Dot comments section! Hope you enjoy it!