Bugzilla Bug 216795

betelgeuse@pena ~ $ irb
irb(main):001:0> require 'rsvg2'
=> true
irb(main):002:0> RSVG.cairo_available?
=> false
irb(main):003:0>

then
emerge -a1v rcairo
emerge -a1v ruby-rsvg

irb(main):001:0> require 'rsvg2'
=> true
irb(main):002:0> RSVG.cairo_available?
=> true
irb(main):003:0>

Portage 2.1.4.4 (default-linux/x86/2006.1/desktop, gcc-4.2.3, glibc-2.7-r2,
2.6.24-gentoo-r3 i686)
=================================================================
System uname: 2.6.24-gentoo-r3 i686 Intel(R) Core(TM)2 CPU 6600 @ 2.40GHz
Timestamp of tree: Unknown
distcc 2.18.3 i686-pc-linux-gnu (protocols 1 and 2) (default port 3632)
[disabled]
ccache version 2.4 [enabled]
app-shells/bash:     3.2_p33
dev-java/java-config: 1.3.7, 2.1.5
dev-lang/python:     2.5.1-r5
dev-util/ccache:     2.4-r7
sys-apps/baselayout: 2.0.0
sys-apps/sandbox:    1.2.18.1-r2
sys-devel/autoconf:  2.13, 2.61-r1
sys-devel/automake:  1.5, 1.7.9-r1, 1.8.5-r3, 1.9.6-r2, 1.10.1
sys-devel/binutils:  2.18-r1
sys-devel/gcc-config: 1.4.0-r4
sys-devel/libtool:   1.5.26
virtual/os-headers:  2.6.24
ACCEPT_KEYWORDS="x86 ~x86"
CBUILD="i686-pc-linux-gnu"
CFLAGS="-O2 -march=native -pipe -fomit-frame-pointer"
CHOST="i686-pc-linux-gnu"
CONFIG_PROTECT="/etc /opt/openjms/config /usr/kde/3.5/env
/usr/kde/3.5/share/config /usr/kde/3.5/shutdown /usr/kde/4.0/env
/usr/kde/4.0/share/config /usr/kde/4.0/shutdown /usr/share/config
/var/lib/hsqldb"
CONFIG_PROTECT_MASK="/etc/env.d /etc/env.d/java/ /etc/fonts/fonts.conf
/etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/splash /etc/terminfo
/etc/texmf/web2c /etc/udev/rules.d"
CXXFLAGS="-O2 -march=native -pipe -fomit-frame-pointer"
DISTDIR="/var/distfiles"
FEATURES="ccache collision-protect distlocks fixpackages parallel-fetch sandbox
sfperms sign strict unmerge-orphans userfetch userpriv usersandbox
verify-rdepend"
GENTOO_MIRRORS=" http://trumpetti.atm.tut.fi/gentoo"
LANG="en_US.utf8"
LC_ALL="en_US.utf8"
LDFLAGS="-Wl,--as-needed -Wl,-O1"
LINGUAS="fi"
PKGDIR="/home/pkg/"
PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress
--force --whole-file --delete --stats --timeout=180 --exclude=/distfiles
--exclude=/local --exclude=/packages"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
PORTDIR_OVERLAY="/mnt/checkouts/overlays/flameeyes-overlay
/mnt/checkouts/overlays/openrc /mnt/checkouts/overlays/jokey
/mnt/checkouts/overlays/postgresql-testing
/mnt/checkouts/overlays/postgresql-experimental
/mnt/checkouts/overlays/betelgeuse"
SYNC="rsync://192.168.150.1/portage"
USE="a52 aac acl acpi alsa audiofile bash-completion berkdb bluetooth branding
bzip2 cairo caps cdb cddb cdparanoia cdr cli cracklib crypt cups dbus dri dts
dvd dvdr dvdread emboss fam ffmpeg firefox gif gstreamer hal iconv isdnlog java
jpeg kde kdeenablefinal kdehiddenvisibility libnotify logitech-mouse mad mikmod
mjpeg mmx mp3 mpeg mudflap ncurses network nptl nptlonly nsplugin nvidia
offensive ogg opengl openmp pam pcre png ppds pppd pulseaudio qt3 quicktime
readline real reflection rtc samba session spell spl sse sse2 ssl
startup-notification subversion svg symlink theora threads truetype udev
unicode usb userlocales vim-syntax vorbis win32codecs x86 xcb xcomposite
xinerama xml xorg xv xvid xvmc zlib" ALSA_CARDS="hda-intel"
ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file
hooks iec958 ioplug ladspa lfloat linear meter mulaw multi null plug rate route
share shm softvol" APACHE2_MODULES="actions alias auth_basic authn_alias
authn_anon authn_dbm authn_default authn_file authz_dbm authz_default
authz_groupfile authz_host authz_owner authz_user autoindex cache dav dav_fs
dav_lock deflate dir disk_cache env expires ext_filter file_cache filter
headers include info log_config logio mem_cache mime mime_magic negotiation
rewrite setenvif speling status unique_id userdir usertrack vhost_alias"
ELIBC="glibc" INPUT_DEVICES="evdev" KERNEL="linux" LCD_DEVICES="bayrad cfontz
cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LINGUAS="fi"
USERLAND="GNU" VIDEO_CARDS="none nvidia"
Unset:  CPPFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, MAKEOPTS,
PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS

Fixed in CVS, thanks for the report.