Are you using 0.7.2c for both gnunet-daemon and gnunet-gtk? I have noticed that in Gutsy, gnunet is 0.7.2c and gnunet-gtk is 0.7.1, which is quite bad! On my two machines, I get this segfault. Installing gnunet-gtk 0.7.2c from debian sid solved the issue. So I thought the version mismatch was the issue.

milan@milan:~$ ldd /usr/bin/gnunet-gtk 
        linux-gate.so.1 =>  (0xffffe000)
        libgtk-x11-2.0.so.0 => /usr/lib/libgtk-x11-2.0.so.0 (0xb7c23000)
        libgdk-x11-2.0.so.0 => /usr/lib/libgdk-x11-2.0.so.0 (0xb7b9c000)
        libatk-1.0.so.0 => /usr/lib/libatk-1.0.so.0 (0xb7b80000)
        libgdk_pixbuf-2.0.so.0 => /usr/lib/libgdk_pixbuf-2.0.so.0 (0xb7b68000)
        libpangocairo-1.0.so.0 => /usr/lib/libpangocairo-1.0.so.0 (0xb7b5f000)
        libfontconfig.so.1 => /usr/lib/libfontconfig.so.1 (0xb7b34000)
        libXext.so.6 => /usr/lib/libXext.so.6 (0xb7b26000)
        libXrender.so.1 => /usr/lib/libXrender.so.1 (0xb7b1e000)
        libXinerama.so.1 => /usr/lib/libXinerama.so.1 (0xb7b1a000)
        libXi.so.6 => /usr/lib/libXi.so.6 (0xb7b12000)
        libXrandr.so.2 => /usr/lib/libXrandr.so.2 (0xb7b0c000)
        libXcursor.so.1 => /usr/lib/libXcursor.so.1 (0xb7b03000)
        libXcomposite.so.1 => /usr/lib/libXcomposite.so.1 (0xb7b00000)
        libXdamage.so.1 => /usr/lib/libXdamage.so.1 (0xb7afd000)
        libpango-1.0.so.0 => /usr/lib/libpango-1.0.so.0 (0xb7abf000)
        libcairo.so.2 => /usr/lib/libcairo.so.2 (0xb7a48000)
        libX11.so.6 => /usr/lib/libX11.so.6 (0xb7957000)
        libXfixes.so.3 => /usr/lib/libXfixes.so.3 (0xb7952000)
        libgobject-2.0.so.0 => /usr/lib/libgobject-2.0.so.0 (0xb7917000)
        libgmodule-2.0.so.0 => /usr/lib/libgmodule-2.0.so.0 (0xb7913000)
        libdl.so.2 => /lib/tls/i686/cmov/libdl.so.2 (0xb790e000)
        libglib-2.0.so.0 => /usr/lib/libglib-2.0.so.0 (0xb7851000)
        libgnunetutil.so.1 => /usr/lib/libgnunetutil.so.1 (0xb7838000)
        libgnunetutil_boot.so.0 => /usr/lib/libgnunetutil_boot.so.0 (0xb7835000)
        libgthread-2.0.so.0 => /usr/lib/libgthread-2.0.so.0 (0xb7830000)
        libgnunetgtk_common.so.0 => /usr/lib/libgnunetgtk_common.so.0 (0xb782a000)
        libm.so.6 => /lib/tls/i686/cmov/libm.so.6 (0xb7805000)
        libnsl.so.1 => /lib/tls/i686/cmov/libnsl.so.1 (0xb77ed000)
        libc.so.6 => /lib/tls/i686/cmov/libc.so.6 (0xb76a3000)
        libglade-2.0.so.0 => /usr/lib/libglade-2.0.so.0 (0xb768b000)
        libpangoft2-1.0.so.0 => /usr/lib/libpangoft2-1.0.so.0 (0xb765d000)
        libfreetype.so.6 => /usr/lib/libfreetype.so.6 (0xb75ec000)
        libz.so.1 => /usr/lib/libz.so.1 (0xb75d7000)
        libexpat.so.1 => /usr/lib/libexpat.so.1 (0xb75b7000)
        libXau.so.6 => /usr/lib/libXau.so.6 (0xb75b4000)
        libpng12.so.0 => /usr/lib/libpng12.so.0 (0xb7591000)
        libXdmcp.so.6 => /usr/lib/libXdmcp.so.6 (0xb758b000)
        /lib/ld-linux.so.2 (0xb7fbd000)
        libgcrypt.so.11 => /usr/lib/libgcrypt.so.11 (0xb753a000)
        libadns.so.1 => /usr/lib/libadns.so.1 (0xb7528000)
        libgmp.so.3 => /usr/lib/libgmp.so.3 (0xb74e3000)
        libcrypt.so.1 => /lib/tls/i686/cmov/libcrypt.so.1 (0xb74b5000)
        libltdl.so.3 => /usr/lib/libltdl.so.3 (0xb74ad000)
        libguile.so.17 => /usr/lib/libguile.so.17 (0xb73db000)
        libpthread.so.0 => /lib/tls/i686/cmov/libpthread.so.0 (0xb73c3000)
        libgnunetutil_config.so.0 => /usr/lib/libgnunetutil_config.so.0 (0xb73be000)
        libgnunetutil_logging.so.0 => /usr/lib/libgnunetutil_logging.so.0 (0xb73ba000)
        librt.so.1 => /lib/tls/i686/cmov/librt.so.1 (0xb73b0000)
        libxml2.so.2 => /usr/lib/libxml2.so.2 (0xb7292000)
        libgnunetutil_crypto.so.0 => /usr/lib/libgnunetutil_crypto.so.0 (0xb7286000)
        libgnunetutil_cron.so.0 => /usr/lib/libgnunetutil_cron.so.0 (0xb7283000)
        libgpg-error.so.0 => /usr/lib/libgpg-error.so.0 (0xb727e000)