Since my bugreport I hadn't experienced the unusually high CPU usage for gconfd-2, but I noticed that the respective process for previously logged user(s) still persists. I don't know if this behaviour is normal or not, but I assume that the high CPU usage comes when the "relict" process has experienced segmentation fault.

For the record here I provide the output of the previously undertaken diagnostics, this time with an apparently intact gconfd-2 process:

$ pidof gconfd-2
6328 6392

[6328 is the remaining process]

$ sudo strace -p 6328
Process 6328 attached - interrupt to quit
futex(0xb7e06320, FUTEX_WAIT, 2, NULL
 <unfinished ...>
Process 6328 detached

$ sudo gdb 2>&1 | tee gdb-gconfd-remaining-process.txt
Password:
GNU gdb 6.4-debian
Copyright 2005 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i486-linux-gnu".
(gdb) handle SIG33 pass nostop noprint
Signal        Stop      Print   Pass to program Description
SIG33         No        No      Yes             Real-time event 33
(gdb) set pagination 0
(gdb) attach 6328
Attaching to process 6328
Reading symbols from /usr/lib/libgconf2-4/gconfd-2...done.
Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1".
Reading symbols from /usr/lib/libORBit-2.so.0...done.
Loaded symbols for /usr/lib/libORBit-2.so.0
Reading symbols from /usr/lib/libglib-2.0.so.0...done.
Loaded symbols for /usr/lib/libglib-2.0.so.0
Reading symbols from /usr/lib/libgconf-2.so.4...done.
Loaded symbols for /usr/lib/libgconf-2.so.4
Reading symbols from /lib/tls/i686/cmov/libpthread.so.0...done.
[Thread debugging using libthread_db enabled]
[New Thread -1211713856 (LWP 6328)]
Loaded symbols for /lib/tls/i686/cmov/libpthread.so.0
Reading symbols from /lib/tls/i686/cmov/libc.so.6...done.
Loaded symbols for /lib/tls/i686/cmov/libc.so.6
Reading symbols from /usr/lib/libgmodule-2.0.so.0...done.
Loaded symbols for /usr/lib/libgmodule-2.0.so.0
Reading symbols from /lib/tls/i686/cmov/libdl.so.2...done.
Loaded symbols for /lib/tls/i686/cmov/libdl.so.2
Reading symbols from /lib/libpopt.so.0...done.
Loaded symbols for /lib/libpopt.so.0
Reading symbols from /usr/lib/libgobject-2.0.so.0...done.
Loaded symbols for /usr/lib/libgobject-2.0.so.0
Reading symbols from /usr/lib/libgthread-2.0.so.0...done.
Loaded symbols for /usr/lib/libgthread-2.0.so.0
Reading symbols from /lib/tls/i686/cmov/libm.so.6...done.
Loaded symbols for /lib/tls/i686/cmov/libm.so.6
Reading symbols from /lib/ld-linux.so.2...done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /lib/tls/i686/cmov/libnss_compat.so.2...done.
Loaded symbols for /lib/tls/i686/cmov/libnss_compat.so.2
Reading symbols from /lib/tls/i686/cmov/libnsl.so.1...done.
Loaded symbols for /lib/tls/i686/cmov/libnsl.so.1
Reading symbols from /lib/tls/i686/cmov/libnss_nis.so.2...done.
Loaded symbols for /lib/tls/i686/cmov/libnss_nis.so.2
Reading symbols from /lib/tls/i686/cmov/libnss_files.so.2...done.
Loaded symbols for /lib/tls/i686/cmov/libnss_files.so.2
Reading symbols from /usr/lib/libgconf2-4/2/libgconfbackend-xml.so...done.
Loaded symbols for /usr/lib/libgconf2-4/2/libgconfbackend-xml.so
0xffffe410 in __kernel_vsyscall ()
(gdb) continue

HTH!