This morning, I added 'URxvt*perl-ext:mark-urls,tabbed' to my ~/.Xdefaults to try out the tabs in rxvt-unicode-7.7-r2. The tabs show up and seem to work fine, but the -rv commandline option seems to now be ignored (it's black on white regardless of the presence of -rv on the commandline). I can add 'URxvt*reverseVideo: true' to ~/.Xdefaults, and the reverse video comes back.
Same thing here. Portage 2.1_rc3-r4 (default-linux/x86/2005.1, gcc-4.1.1, glibc-2.4-r3, 2.6.16-ck11 i686) ================================================================= System uname: 2.6.16-ck11 i686 Intel(R) Celeron(R) CPU 2.60GHz Gentoo Base System version 1.12.0 dev-lang/python: 2.3.5-r2, 2.4.3-r1 dev-python/pycrypto: 2.0.1-r5 dev-util/ccache: [Not Present] dev-util/confcache: 0.4.2-r1 sys-apps/sandbox: 1.2.18.1 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-r2 sys-devel/binutils: 2.16.1-r2 sys-devel/libtool: 1.5.22 virtual/os-headers: 2.6.11-r5 ACCEPT_KEYWORDS="x86 ~x86" AUTOCLEAN="yes" CBUILD="i686-pc-linux-gnu" CFLAGS="-march=i686 -O2 -pipe" CHOST="i686-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/NX/etc /usr/NX/home /usr/kde/3.5/env /usr/kde/3.5/share/config /usr/kde/3.5/shutdown /usr/share/X11/xkb /usr/share/config" CONFIG_PROTECT_MASK="/etc/gconf /etc/revdep-rebuild /etc/terminfo /etc/env.d" CXXFLAGS="-march=i686 -O2 -pipe" DISTDIR="/usr/portage/distfiles" FEATURES="autoconfig ccache confcache distlocks fixpackages metadata-transfer parallel-fetch prelink sandbox sfperms strict" GENTOO_MIRRORS="http://ftp.belnet.be/mirror/rsync.gentoo.org/gentoo/ http://ftp.snt.utwente.nl/pub/os/linux/gentoo http://mir.zyrianes.net/gentoo/ http://pandemonium.tiscali.de/pub/gentoo/" LANG="fr_FR.UTF-8" LDFLAGS="-Wl,-O1 -Wl,--as-needed" LINGUAS="fr fr_FR" MAKEOPTS="-j2" PKGDIR="/usr/portage/packages" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --delete-after --stats --timeout=180 --exclude='/distfiles' --exclude='/local' --exclude='/packages'" PORTAGE_TMPDIR="/var/tmp" PORTDIR="/usr/portage" PORTDIR_OVERLAY="/usr/local/portage" SYNC="rsync://192.168.25.45/gentoo-portage" USE="x86 X a52 aac aim alsa apm avi bash-completion berkdb bitmap-fonts bonobo browserplugin bzip2 cairo cddb cdr cli crypt cscope cups curl dbus dga dio dlloader dri dts dvb dvd dvdread emboss encode exif expat ffmpeg fftw firefox flac foomaticdb fortran ftp gb gcj gdbm gif gimp glut gnome gnustep gnutls gpm gstreamer gtk gtk2 gtkhtml iconv idn imap imlib ipv6 isdnlog jabber java jikes joystick jpeg lcms libcaca libg++ libwww live mad matroska mbox mikmod mime mmx mng mono mp3 mpeg msn musicbrainz ncurses nls nptl nptlonly nsplugin nvidia objc offensive ogg oggvorbis openal opengl oscar oss pam pcre pda pdflib perl php pic png posix ppds pppd python qt quicktime readline real recode reflection ruby samba sdl session spell spl sqlite sse sse2 ssl svg tcpd theora threads tiff truetype truetype-fonts type1-fonts unicode usb v4l vcd vorbis wifi win32codecs wmf wxwindows x264 xface xinerama xml xml2 xmms xorg xosd xv xvid yahoo zlib elibc_glibc input_devices_keyboard input_devices_mouse input_devices_evdev kernel_linux linguas_fr linguas_fr_FR userland_GNU video_cards_radeon video_cards_i810" Unset: CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LC_ALL, PORTAGE_RSYNC_EXTRA_OPTS
it's not ignored, tabbed uses different resources for background/foreground; see the tabbed documentation in urxvtperl(3).