FireWire is the consumer name for the IEEE1394 protocol. Sony call it i.Link.

It is a serial bus protocol, with a capacity of up to 400Mbps, or 800Mbps in the IEEE1394-b standard (known as FireWire800). FireWire can support up to 63 chained devices.

FireWire is typically used for digital video systems (DV) to connect the camera to a computer. It's high speed allows rapid download of DV to a host system. It's also used for external harddisks, scanners, and can be used to connect two computers together.

You can use gscanbus to see what is plugged into your FireWire port.

If you are trying to use a FireWire device with your applications remember to set the right permissions on /dev/video1394 and /dev/raw1394 and check that they exist with those names and not similar (I had to symlink to create one). If you don't do this GnomeMeeting? won't work but doesn't give error messages either....