Version:           3.5.2! (using KDE Devel)
Installed from:    Compiled sources
Compiler:          gcc 3.4.4 -O2 -march=pentium-m -pipe -mmmx -msse -msse2 -fomit-frame-pointer (compiled without arts)
OS:                Linux

Somewhere between kernel (headers) 2.6.15 and 2.6.16 this change was done: http://www.linuxhq.com/kernel/v2.6/15-git4/include/linux/input.h in include/linux/input.h
Due to this (i believe), kde wont compile if you have the 2.6.16 kernel headers (but it will with 2.6.11 and probably all the way up to 2.6.15)

The error is:
make[3]: Leaving directory `/var/tmp/portage/kcontrol-3.5.2/work/kcontrol-3.5.2/kcontrol/kthememanager' 
Making all in joystick 
make[3]: Entering directory `/var/tmp/portage/kcontrol-3.5.2/work/kcontrol-3.5.2/kcontrol/joystick' 
/usr/qt/3/bin/moc ./joystick.h -o joystick.moc 
/bin/sh ../../libtool --silent --mode=compile --tag=CXX i686-pc-linux-gnu-g++ -DHAVE_CONFIG_H -I. -I. -I../..  -I/usr/kde/3.5/include -I/usr/qt/3/include -I.  -DQT_THREAD_SUPPORT  -D_REENTRANT  -Wno-long-long -Wundef -ansi -D_XOPEN_SOURCE=500 -D_BSD_SOURCE -Wcast-align -Wconversion -Wchar-subscripts -Wall -W -Wpointer-arith -DNDEBUG -DNO_DEBUG -O2 -O2 -march=pentium-m -pipe -mmmx -msse -msse2 -fomit-frame-pointer -Wformat-security -Wmissing-format-attribute -Wno-non-virtual-dtor -fno-exceptions -fno-check-new -fno-common -DQT_CLEAN_NAMESPACE -DQT_NO_ASCII_CAST -DQT_NO_STL -DQT_NO_COMPAT -DQT_NO_TRANSLATION  -c -o joystick.lo `test -f 'joystick.cpp' || echo './'`joystick.cpp 
In file included from /usr/include/linux/joystick.h:33, 
                 from joydevice.h:27, 
                 from joystick.cpp:29: 
/usr/include/linux/input.h:801: error: `kernel_ulong_t' does not name a type 
/usr/include/linux/input.h:805: error: `kernel_ulong_t' does not name a type 
/usr/include/linux/input.h:806: error: `kernel_ulong_t' does not name a type 
/usr/include/linux/input.h:807: error: `kernel_ulong_t' does not name a type 
/usr/include/linux/input.h:808: error: `kernel_ulong_t' does not name a type 
/usr/include/linux/input.h:809: error: `kernel_ulong_t' does not name a type 
/usr/include/linux/input.h:810: error: `kernel_ulong_t' does not name a type 
/usr/include/linux/input.h:811: error: `kernel_ulong_t' does not name a type 
/usr/include/linux/input.h:812: error: `kernel_ulong_t' does not name a type 
/usr/include/linux/input.h:813: error: `kernel_ulong_t' does not name a type 
/usr/include/linux/input.h:815: error: `kernel_ulong_t' does not name a type 
make[3]: *** [joystick.lo] Error 1 
make[3]: Leaving directory `/var/tmp/portage/kcontrol-3.5.2/work/kcontrol-3.5.2/kcontrol/joystick' 
make[2]: *** [all-recursive] Error 1 
make[2]: Leaving directory `/var/tmp/portage/kcontrol-3.5.2/work/kcontrol-3.5.2/kcontrol' 
make[1]: *** [all-recursive] Error 1 
make[1]: Leaving directory `/var/tmp/portage/kcontrol-3.5.2/work/kcontrol-3.5.2' 
make: *** [all] Error 2 

!!! ERROR: kde-base/kcontrol-3.5.2 failed.

As you can see in the diff, unsigned int was changed to kernel_ulong_t and this prevents kdebase/kcontrol from compiling.

and BTW: bugs.kde.org should be updated with listing 3.5.2 in the list of versions, i had to chose 3.5.1 when filing this bug.