Version: (using KDE 4.1.0) Installed from: Ubuntu Packages OS: Linux To acces the Vsync checkbox for Desktop Effects, You can right click on any window and choose "Configure window behavior" or using systemsettings by NOT clicking on "Window Behavior" but on "Desktop" ... this is very confusing, one of the two should change , or desktop effects part of Desktop config moved to Window Behavior in systemsettings....
The "configure window behaviour" gives access to all KWin settings. These settings relate to different parts of KDE and are by that split in systemsettings. So you find for example window decoration in appearance.
This is intentional (as Martin points out) :)
Bulk change: move all KWin kcm bugs to product kwin