subject says it all.

Downloading ftp://ftp.tu-clausthal.de/pub/linux/gentoo//distfiles/libungif-4.1.0.tar.gz
...
!!! Couldn't download libungif-4.1.0.tar.gz. Aborting.

looks l ike the mirrors missing libungif?
my temp fix:

cd /usr/portage/distfiles
wget http://ftp.rge.com/pub/multimedia/libungif/libungif-4.1.0.tar.gz
emerge -u gnome


make.conf info
---------------------

USE="alsa aalib apache2 arts avi bonobo cdr cjk crypt cups dga directfb dvd encode esd fbcon flash gb gd gdbm ggi gif gnome gpm gk gtk gtk2 gtkhtml guile java jikes jpeg junit kde ldap libg++ libgda libwww maildir mmx motif mozilla mpeg mysql nas ncurses ndl odbc oggvorbis opengl oss pam pdflib perl pic png pnp postgres python qt qtmt quicktime readline samba sasl scanner sdl slang slp snmp socks5 spell sse ssl static svga tcltk tcpd tetex tiff truetype usb wmf X xml xml2 xmms xv zeo zlib x86"
GENTOO_MIRRORS=" http://ftp.easynet.nl/mirror/gentoo// ftp://ftp.easynet.nl/mirror/gentoo// ftp://ftp.tu-clausthal.de/pub/linux/gentoo/"
CFLAGS="-O3 -mcpu=i686 -pipe"
dunno why this is gnome, its a mirror thing. but the SRC_URI has been updated to a work URL now. please try again.