Well, in 2006 the International Astronomical Union adopted these standards for classification as a planet:
- is in orbit around the Sun,
- has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
- has "cleared the neighbourhood" around its orbit
Hopefully, in the next decades, we will be able to learn more about planets in other solar systems and many of them will be much more interesting than Pluto. Actually, we already know of more interesting stuff here in our solar system. Jupiter's moon Europa is made of a rock core covered in ice, and it is thought that the surface of Europa might obscure a liquid water ocean http://www.solarviews.com/eng/europa.htm
due to the heat produced from shape changing caused by Jupiter's gravitational pull. Time will tell. Hopefully someday we'll get a probe on there to drill for water!