To what end? To have new KDE4 release in Debian at the same moment I have them in Windows, not 6 months later for example (this argument I've already given at least once in LWN).
I don't take notes, but I've seen it in other places too: source and Windows releases of software are at version x.2 while .deb file is at x.0. Also, beta builds are many times only available for Windows and OSX. Being able to run multiple versions is useful at times, but let's skip this argument as it's more complex.