Built on RHEL from latest SVN Sources.  lame is installed from latest source as well as all other libraries.
but the output of the command below doesn't list libmp3lame and I cannot encode mp3 audio. 

I get the message: Unknown encoder 'libmp3lame'


# ffmpeg -formats | grep mp3
FFmpeg version SVN-r10145, Copyright (c) 2000-2007 Fabrice Bellard, et al.
  configuration: --enable-libxvid --enable-libogg --enable-libvorbis --enable-libamr-nb --enable-libamr-wb --enable-libfaac --enable-libfaad --enable-gpl --enable-shared --enable-libmp3lame --enable-encoder=libmp3lame --extra-cflags=-I/local/include --extra-ldflags=-L/local/lib
  libavutil version: 49.5.0
  libavcodec version: 51.41.0
  libavformat version: 51.12.2
  built on Aug 20 2007 22:48:56, gcc: 3.4.6 20060404 (Red Hat 3.4.6-8)
 DE mp3             MPEG audio layer 3
 D A    mp3
 D A    mp3adu
 D A    mp3on4