Modifiqué los repositorios, según me quié por el link
http://pkg-kde.alioth.debian.org/experimental.html :
#Sid para instalar KDE 4.0
deb
http://ftp.us.debian.org/debian/ sid main contrib non-free
deb-src
http://ftp.us.debian.org/debian/ sid main non-free contrib
deb
http://ftp.us.debian.org/debian/ experimental main non-free contrib
deb-src
http://ftp.us.debian.org/debian/ experimental main non-free contrib
# Official Debian Sites
#### Testing ######
deb
http://http.us.debian.org/debian testing main contrib non-free
deb
http://non-us.debian.debian.org/debian-non-US testing/non-US main contrib non-free
#### Unstable #####
deb
http://ftp.us.debian.org/debian unstable main non-free contrib
deb
http://non-us.debian.org/debian-non-US unstable/non-US main contrib non-free
Ahora estoy actualizandolo con :
#apt-get update
Pero, para instalar KDE 4.0, los instalo con :
1) apt-get install kde
ó
2) apt-get dist-upgrade