I got the same thing with gnome x64, maybe it only works for kde? I don't think the cp command would work either way though, there's no destination folder given. What is it supposed to be?
root@bt:~# prepare-kernel-sources[*] apt-getting linux-source...
Reading package lists... Done
Building dependency tree
Reading state information... Done
linux-source is already the newest version.
The following packages were automatically installed and are no longer required:
libecryptfs0 libdmraid1.0.0.rc16 libdebconfclient0 ecryptfs-utils cryptsetup
rdate bogl-bterm libdebian-installer4 reiserfsprogs dmraid python-pyicu
Use 'apt-get autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.[*] extracting sources, please wait[*] doing stuff...
cp: missing destination file operand after `/boot/'
Try `cp --help' for more information.
scripts/kconfig/conf --silentoldconfig Kconfig
CALL scripts/checksyscalls.sh[*] tada!
root@bt:/usr/src/linux# more /usr/bin/prepare-kernel-sources
echo "[*] apt-getting linux-source..."
apt-get install linux-source
echo "[*] extracting sources, please wait"
tar jxpf linux-source-$VER.tar.bz2
echo "[*] doing stuff..."
rm -rf linux
ln -s linux-source-$VER linux
zcat /proc/config.gz > .config
ln -s /usr/src/linux /lib/modules/$VER/build
echo "[*] tada!"