Just when the Pluto debate was dying down and we thought people might not be caring quite so much about what is and isn't a planet, another object comes along to blur the definition. But this time, it's on the other end of the spectrum.
The Hubble has recently imaged an object around a nearby red dwarf star that is estimated to have about 12 times the mass of Jupiter. This brings up the question of whether it's a planet or a star. It's generally accepted that any object capable of any sort of fusion at any time in its life so far, will be considered a star.
The reason this new object blurs the line is that deuterium fusion (deuterium being an istope of hydrogen containing a neutron in the nucleus) starts occuring somewhere right about 12 Jupiter masses. Precisely where that line is, is not terribly well known as the insides of stars are very complex places (as my astrophyics course this semester has been demonstrating).
Thus, the designation for this new object still needs to be hammered out.