The first reporting of the confirmed discovery of a star outside our own Solar system, with a planet orbiting around it (known as an extrasolar planetary system), was in 1995. Michel Mayor and Didier Queloz reported their finding on October 6th at the 9th Cambridge workshop on "cool stars, stellar systems, and the sun" held in Florence in Italy. This was based on a year of very precise Doppler measurements between September 1994 and September 1995, performed with the ELODIE spectrograph of the Observatoire de Haute-Provence of France. The new planet is half the mass of Jupiter.
Prior to Mayor and Queloz's discovery, Polish astronomer Aleksander Wolszczan claimed to have found the first extra-solar planet in 1993, orbiting the pulsar PSR 1257+12. This planet was formally confirmed to exist in 2003. The planet's has been designated PSR B1620-26c. Although it does not have an official name, it has been given the nickname Methuselah (this has not yet been accepted by the International Astronomical Union). It is likely that Methuselah is about 12.7 billion years old - nearly three times as old as Earth.
Since those first early discoveries, as at the time writing this page, 10 October 2004, there have been 117 extrasolar planetary systems found. Of these, 13 systems have been detected as having multiple planets, and an overall total of 133 planets have been identified. The discoveries aren't just in one particular area but are scattered all over the sky.
Currently all of the planets found are giant planets like Jupiter and Saturn. One thing that has surprised scientists is that unlike our own solar system, in other systes there are large planets orbiting as close to their star as as mercury is to the sun.
It was was originally believed that giant planets would only be found on the outside of system as, according to scientific models, the outer distances far from the central star is the only is the only place that these giants can form. It is now thought that the large planets which have been detected close to their parent stars form in the outer distances but then spiral inwards and may even fall into a star. This theory initially brought up another question however - with the huge size of the giant planets, wouldn't they just swallow up any smaller earth-like planets as the giants spiralled from the outer distances toward the star? Fortunately the latest models show that the giants form faster than the earth-like planets, so the already-formed giant planets can plough through space debris which later comes together to form an earth-like planet.