Look at newer project, called FmStick. Its digital USB-FM Transmitter

This is application to control si471x FM transmitter IC

Hardware options:

• i2c interface (through i2c-tiny-usb).
• Up to 1W power output.
• Analog or SPDIF audio input.

Software options:

udpshout - is a simple application, that takes an MPEG transport stream from a multicast/unicast UDP network stream (like IPTV), extracts audio channels from stream, and sends the audio to an Icecast/Shoutcast server.

The HTTP streams can be played back in most MPEG Audio players (eg iTunes, WinAmp, VLC, Mplayer, Xmms etc).

News

NEWS 2010-03-06:

To install module (before kernel 2.6.25) do:

# apt-get install mecurial
# hg clone http://linuxtv.org/hg/~tlorenz/v4l-dvb/
# make
# make install
# reboot

To bind device to right module, do:

# ls  /sys/bus/usb/drivers/usbhid
My device number - is 1-10:1.2
# echo -n '1-10:1.2' > /sys/bus/usb/drivers/usbhid/unbind
# echo -n '1-10:1.2' > /sys/bus/usb/drivers/radio-si470x/bind

You can capture from tuner:

arecord -D plughw:1,0 -c 2 -r 96000 -f S16_LE -