The ebuild for Shapelib appears to not create a necessary symlink, causing some programs that link against it to fail to detect. In my case, I was compiling the Xastir software from their CVS repository, and configure, when trying to test for Shapelib was giving -lshp not found. Running the following command in /usr/lib allowed Shapelib to be detected: ln -s libshp.so.1.0.1 libshp.so emerge --info output: vulcan ~ # emerge --info Portage 2.1_pre4-r1 (default-linux/amd64/2005.1, gcc-3.4.5, glibc-2.3.6-r2, 2.6.16-rc3-xen0 x86_64) ================================================================= System uname: 2.6.16-rc3-xen0 x86_64 AMD Athlon(tm) 64 Processor 3000+ Gentoo Base System version 1.12.0_pre16 dev-lang/python: 2.3.5-r2, 2.4.2-r1 sys-apps/sandbox: 1.2.17 sys-devel/autoconf: 2.13, 2.59-r7 sys-devel/automake: 1.4_p6, 1.5, 1.6.3, 1.7.9-r1, 1.8.5-r3, 1.9.6-r1 sys-devel/binutils: 2.16.1-r1 sys-devel/libtool: 1.5.22 virtual/os-headers: 2.6.11-r3 ACCEPT_KEYWORDS="amd64 ~amd64" AUTOCLEAN="yes" CBUILD="x86_64-pc-linux-gnu" CFLAGS="-O2 -march=k8 -pipe -fomit-frame-pointer" CHOST="x86_64-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/kde/2/share/config /usr/kde/3.5/env /usr/kde/3.5/share/config /usr/kde/3.5/shutdown /usr/kde/3/share/config /usr/lib/X11/xkb /usr/lib64/mozilla/defaults/pref /usr/share/config /var/qmail/control" CONFIG_PROTECT_MASK="/etc/gconf /etc/terminfo /etc/texmf/web2c /etc/env.d" CXXFLAGS="-O2 -march=k8 -pipe -fomit-frame-pointer" DISTDIR="/usr/portage/distfiles" FEATURES="autoconfig distlocks sandbox sfperms strict" GENTOO_MIRRORS="http://distfiles.gentoo.org http://distro.ibiblio.org/pub/linux/distributions/gentoo" MAKEOPTS="-j3" PKGDIR="/usr/portage/packages" PORTAGE_TMPDIR="/var/tmp" PORTDIR="/usr/portage" SYNC="rsync://rsync.gentoo.org/gentoo-portage" USE="amd64 X a52 aalib acpi alsa audiofile avi berkdb bitmap-fonts cairo cdparanoia cdr crypt cups curl dbus dvd dvdr dvdread eds emboss encode esd fame ffmpeg flac foomaticdb fortran gcj gdbm gif gimpprint glitz gnome gpm gs gstreamer gtk gtk2 guile hal howl imagemagick imlib ipv6 javascript jpeg kde lcms lzw lzw-tiff mad mjpeg moznocompose moznoirc moznomail mozsvg mp3 mpeg nautilus ncurses nls nptl nptlonly nsplugin nvidia offensive ogg opengl pam pdflib perl png python qt quicktime readline samba sdl slang spell ssl svg t1lib tcltk tcpd theora threads tiff truetype truetype-fonts type1-fonts unicode usb userlocales vcd vorbis xml2 xpm xv xvid zlib elibc_glibc kernel_linux userland_GNU" Unset: ASFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, LANG, LC_ALL, LDFLAGS, LINGUAS, PORTDIR_OVERLAY
Try the updated ebuild; it should be 64-bit clean now (brain-dead static Makefiles...)