rpm -qa --qf="%{SIZE}\t%{NAME}\n" | sort -g
0	DeviceKit-power
0	filesystem
0	gpg-pubkey
0	gpg-pubkey
0	gpg-pubkey
0	gpg-pubkey
0	gpg-pubkey
0	gpg-pubkey
0	gpg-pubkey
0	gpg-pubkey
0	gpg-pubkey
70	openSUSE-release-ftp
4205	glib2-branding-Moblin
7367	openSUSE-build-key
8258	master-boot-code
9716	xorg-x11-libXau
13369	ulimit
13848	libgmodule-2_0-0
17836	xorg-x11-libXfixes
18068	xorg-x11-libXv
18076	libcap2
18100	libgthread-2_0-0
18136	libuuid1
18654	libattr
21996	xorg-x11-libXdmcp
22024	libogg0
22140	libzio
24184	xorg-x11-libfontenc
24496	mingetty
26268	libdaemon0
27910	update-alternatives
30224	xorg-x11-libSM
30444	libasm1
31584	libgudev-1_0-0
31742	libaio
32688	libnscd
34444	libcdda_paranoia0
34464	libcrack2
34468	xorg-x11-libXprintUtil
34544	libacl
34704	xorg-x11-libXp
35472	libgssglue1
36068	keyutils-libs
36096	libcom_err2
36535	fillup
38668	xorg-x11-libXrender
41005	polkit-default-privs
41351	utempter
43594	setserial
45024	libesd0
45788	hicolor-icon-theme
46904	libdevkit-power-gobject1
47986	pm-profiler
54689	gdbm
58256	libusb-0_1-4
58521	klogd
58996	libXi6
59100	libudev0
65325	insserv
67408	libupower-glib1
72100	libcdda_interface0
72468	xorg-x11-libXext
75416	zlib
75939	acpid
79387	libatasmart4
81832	libpopt0
82333	gpart
82737	libbz2-1
83641	openSUSE-release
85780	libassuan0
87109	ifplugd
87381	keyutils
90582	dhcpcd
91828	libelf1
92048	libadns1
92558	libaudit1
93252	bzip2
94747	libmspack0
94887	permissions
96224	libcryptsetup1
96796	xorg-x11-libICE
97752	sysvinit
98040	libgstapp-0_10-0
101688	libxcrypt
105310	sysfsutils
110334	libgpg-error0
112344	xorg-x11-libXpm
114956	xorg-x11-libXmu
116348	libgcc45
117607	polkit
119107	libreiserfs
120868	libselinux1
124827	attr
126448	libx86emu1
129356	libblkid1
140812	liblzo2-2
140850	openslp
143051	libusb-1_0-0
148187	cracklib
149120	liblzma0
150040	xorg-x11-libxkbfile
150519	pciutils
151059	pinentry
154489	mkinitrd
156560	ncurses-utils
157684	libssh2-1
158525	ethtool
160266	libtirpc1
163348	libenca0
165372	libexpat1
167001	hdparm
169061	dbus-1-glib
173936	libpng14-14
184096	pkg-config
185840	libpcre0
186566	gzip
189478	xdg-utils
194212	acl
194452	libpth20
195228	liblua5_1
200021	tcpd
201478	xz
203844	upower
207510	iputils
216520	libaugeas0
221512	cpio
223216	libdw1
227072	libjpeg8
230728	libext2fs2
235336	libevent-1_4-2
239879	cryptsetup
245721	psmisc
250839	pcre
252040	libsepol1
257448	audiofile
265827	strace
267312	less
279553	module-init-tools
281163	libksba
281440	libreadline6
284561	xinetd
289030	info
291528	curl
293008	libgobject-2_0-0
294026	login
303539	perl-Bootloader
304759	ConsoleKit
312622	aaa_base
319553	libeggdbus-1-0
329311	vim-base
352261	pm-utils
353844	device-mapper
355152	libcurl4
380128	xorg-x11-libXt
396095	PolicyKit
417310	libtiff3
426500	libvisual
435658	sysvinit-tools
436196	findutils
436320	pam-config
458450	libpixman-1-0
468563	pam-modules
494656	libpolkit0
498552	sed
504396	dirmngr
506066	gpm
508832	libSDL-1_2-0
510605	liboil
519403	sudo
537820	xorg-x11-libxcb
573868	openldap2-client
586464	libsqlite3-0
593503	procps
632896	grep
644056	libgcrypt11
658311	pciutils-ids
666333	bash
668920	udisks
669644	libldap-2_4-2
682357	libatk-1_0-0
697120	libtheora0
714659	sysconfig
717278	glib2
741084	net-tools
753108	libgio-2_0-0
792153	elfutils
796874	netcfg
811403	dbus-1
833441	libidn
890263	rsync
923230	diffutils
932516	libncurses5
936564	libglib-2_0-0
949626	udev
950760	libstdc++45
975744	parted
992145	rsyslog
1034941	terminfo-base
1045599	libfreetype6
1057188	fontconfig
1058931	libasound2
1095778	tar
1167833	iptables
1230175	cyrus-sasl
1233800	libvorbis
1237524	joe
1257515	openssl
1305454	sg3_utils
1325548	libdb-4_5
1451506	grub
1470634	pam
1517278	cairo
1519795	pango
1551823	libxml2
1567745	libgstinterfaces-0_10-0
1622716	krb5
1631964	hal
1729355	iproute2
1752837	w3m
1767476	util-linux
1769799	satsolver-tools
1846805	gawk
1876386	pwdutils
1955111	e2fsprogs
1955743	xorg-x11-libs
2019471	hwinfo
2247243	gettext-runtime
2294426	gstreamer-0_10-plugins-base
2295580	libopenssl1_0_0
2398703	bundle-lang-common-en
2476270	kbd
2494748	file
2504604	gstreamer-0_10
2617724	openssh
2900162	libgstreamer-0_10-0
2987656	bind-libs
3471099	cups-libs
3673910	rpm
4050717	gpg2
4425087	coreutils
4431335	zypper
4725631	aria2
4831172	glibc
4897634	perl-base
7052894	libzypp
10970118	cracklib-dict-full
11275317	xorg-x11-libX11
13377209	gtk2
13444946	wxGTK
14718820	codeblocks
102836358	kernel-desktop
---------------

rpm -qa --qf="%{SIZE}\n" | perl -ne 'END{print$x}$x+=$_'
323162211 = 308 MB

df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda2              3622424    507336   2931076  15% /
devtmpfs                250688       152    250536   1% /dev
tmpfs                   250900         4    250896   1% /dev/shm

Most likely the ext4 overhead...

du -hsx /
421M

Some of that is /var/cache that is of course not tracked with rpm.