ffmpeg output to multiple files simultaneously

I use

ffmpeg -f lavfi -re -i 'life=s=300x200:mold=10:r=25:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16' \
-f lavfi -re -i sine=frequency=1000:sample_rate=44100 -pix_fmt yuv420p \
-c:v libx264 -b:v 1000k -g 30 -keyint_min 60 -profile:v baseline -preset veryfast -c:a aac -b:a 96k  \
-f flv "rtmp://yourname.com:1935/live/stream1" \
-f flv "rtmp://yourname.com:1935/live/stream2" \
-f flv "rtmp://yourname.com:1935/live/stream3" \

The ffmpeg documentation has been updated with lots more information about this and options depend on the version of ffmpeg you use: http://ffmpeg.org/trac/ffmpeg/wiki/Creating%20multiple%20outputs

From FFMpeg documentation, FFmpeg writes to an arbitrary number of output "files".

Just make sure each output file (or stream), is preceded by the proper output options.