FFmpeg can basically stream through one of several ways: It either streams to an instance of ffserver, which serves out the streams (not available in windows, at least yet), or it streams to any rtmp server (ex: wowza, flash media server, etc.), or it can stream via UDP directly to some receiving host. It can even stream to an instance of VLC, which picks up the stream, then redistributes it as the server. Since ffmpeg is sometimes more efficient than VLC at encoding, this can be a useful option.

Here's how one guy broadcast a live stream:

$ ffmpeg -y -loglevel warning -f dshow -i video="screen-capture-recorder" -vf crop=690:388:136:0 -r 30 -s 962x388 -threads 2 -vcodec libx264 -vpre baseline -vpre my_ffpreset -f flv rtmp:///live/myStream.sdp

Here is my ffmpeg preset (libx264-my_ffpreset.ffpreset):
coder=1
flags2=+wpred+dct8x8
level=31
maxrate=1200000
bufsize=200000
wpredp=0
g=60
refs=1
subq=3
trellis=0
bf=0
rc_lookahead=0

How to stream with several different is described  here.