[FFmpeg-user] 5.1 -> mp3 loses the "effects" .1 channel?

[Roger Pack]

Hello all.
I noticed that with this file:

http://rogerdpack.t28.net/incoming/9.wav

and the below conversion to mp3, it correctly "merges" the 5 audio
channels, but seems to discard the "effects" .1 channel.
Anybody know if this is expected?
Thanks!
-roger-

C:\ffmpeg-20120903-git-5d55830-win32-static\bin\ffmpeg -i C:\temp\9.wav yo.mp3
ffmpeg version N-44123-g5d55830 Copyright (c) 2000-2012 the FFmpeg developers
  built on Sep  2 2012 20:23:29 with gcc 4.7.1 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-pthreads
--enable-runtime-cpudetect --enable-avisynth --enable-bzlib
--enable-frei0r --enable-libass --enable-libcelt
--enable-libopencore-amrnb --enable-libopencore-amrwb
--enable-libfreetype --enable-libgsm --enable-libmp3lame
--enable-libnut --enable-libopenjpeg --enable-librtmp
--enable-libschroedinger --enable-libspeex --enable-libtheora
--enable-libutvideo --enable-libvo-aacenc --enable-libvo-amrwbenc
--enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs
--enable-libxvid --enable-zlib
  libavutil      51. 70.100 / 51. 70.100
  libavcodec     54. 55.100 / 54. 55.100
  libavformat    54. 25.104 / 54. 25.104
  libavdevice    54.  2.100 / 54.  2.100
  libavfilter     3. 15.102 /  3. 15.102
  libswscale      2.  1.101 /  2.  1.101
  libswresample   0. 15.100 /  0. 15.100
  libpostproc    52.  0.100 / 52.  0.100
[wav @ 0038c5c0] max_analyze_duration 5000000 reached at 5001333
Input #0, wav, from 'C:\temp\9.wav':
  Duration: 00:00:14.79, bitrate: 4608 kb/s
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz,
5.1, s16, 4608 kb/s
File 'yo.mp3' already exists. Overwrite ? [y/N] y
Output #0, mp3, to 'yo.mp3':
  Metadata:
    TSSE            : Lavf54.25.104
    Stream #0:0: Audio: mp3, 48000 Hz, stereo, s16
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le -> libmp3lame)
Press [q] to stop, [?] for help
size=     232kB time=00:00:14.80 bitrate= 128.3kbits/s
video:0kB audio:232kB subtitle:0 global headers:0kB muxing overhead 0.095655%