I was surprised that heartbeat didn't have an amd64 keyword.
I used ekeyword to add ~amd64 to the ebuild version heartbeat-1.2.3. The build happened with no hitch.
sysinfo:
prod-ldap-atl03 root # emerge info
Portage 2.0.51-r15 (default-linux/amd64/2004.3, gcc-3.4.3, glibc-2.3.4.20040808-r1, 2.6.9-gentoo-r14cti-opteron-smp x86_64)
=================================================================
System uname: 2.6.9-gentoo-r14cti-opteron-smp x86_64 AMD Opteron(tm) Processor 240
Gentoo Base System version 1.4.16
Python: dev-lang/python-2.3.4 [2.3.4 (#1, Jan 25 2005, 05:08:59)]
dev-lang/python: 2.3.4
sys-devel/autoconf: 2.59-r5
sys-devel/automake: 1.8.5-r1
sys-devel/binutils: 2.15.92.0.2-r1
sys-devel/libtool: 1.5.2-r7
virtual/os-headers: 2.6.8.1-r2
ACCEPT_KEYWORDS="amd64"
AUTOCLEAN="yes"
CFLAGS="-march=opteron -O3 -pipe"
CHOST="x86_64-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/kde/2/share/config /usr/kde/3/share/config /usr/share/config /var/qmail/control"
CONFIG_PROTECT_MASK="/etc/gconf /etc/terminfo /etc/env.d"
CXXFLAGS="-march=opteron -O3 -pipe"
DISTDIR="/usr/portage/distfiles"
FEATURES="autoaddcvs autoconfig ccache distlocks sandbox"
GENTOO_MIRRORS="http://ebiz-randd.cti-pet.com/mirrors/gentoo http://gentoo.osuosl.org http://www.ibiblio.org/pub/Linux/distributions/gentoo"
MAKEOPTS="-j3"
PKGDIR="/usr/portage/packages"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
PORTDIR_OVERLAY="/usr/local/portage"
SYNC="rsync://ebiz-randd.cti-pet.com/gentoo-portage"
USE="amd64 acpi berkdb bitmap-fonts crypt f77 fam font-server fortran gdbm gif gpm ipv6 jp2 jpeg ldap lzw lzw-tiff multilib ncurses nls nptl opengl oss pam perl png python readline sasl slp snmp ssl tcpd threads tiff truetype truetype-fonts type1-fonts usb userlocales xml2 xpm xrandr xv zlib"
Unset: ASFLAGS, CBUILD, CTARGET, LDFLAGS
