These items should be in your /etc/rc.conf in order to get KDE to behave normally in BSD.  This is true for freeBSD 8.1 on Klaatu's test system.  How PC-BSD does it is probably worth looking into, but I'm not running that so......shrug!

hald_enable="YES"
dbus_enable="YES"
local_startup="${local_startup} /usr/local/kde4/etc/rc.d"
kdem4_enable="YES"