You sometimes, if you're lucky, see 3 satellites strung together.
The flash you see from Iridium Satellites is caused by the sun reflecting off their panels.
An Iridium Flare can be an awesome event. You can find out when and where they will occur in your location, as well as times for pass overs for the International Space Station and Hubble Telescope by logging on to
www.heavens-above.com