No persuasion possible
"That's still smaller than Earth's moon, at 3,475 km – so sorry, Pluto fans, you still won't persuade academic astronomy to upgrade it back to being called a planet."
Even if it were larger than Jupiter, Pluto would not be a planet by the IAU definition, not having cleared its orbit of other objects. On the other hand, of course, any object with the mass of Jupiter would have done so pretty early on. The IAU definition also has no definition based on size as such, only that the object to be called a planet would have to be in near hydrostatic equilibrium, i.e., shaped near-spherically due to the gravity induced by its own mass.
I am somewhat saddened by the many people who insist on categorising Pluto as a planet, when the reason the IAU formed a group to hammer out a binding definition of the term "planet" for the first time was the discovery not only of many approximately Pluto-sized objects beyond Neptune (the TNOs or Trans-Neptunian Objects, most of which turned out to be part of what is now called the Kuiper Belt), but also that there are several objects co-orbiting with Pluto which are not orbiting Pluto at the same time.
The IAU did not, as I once heard from a fellow hobby astronomer, "vindictively downgrade Pluto," but they for the first time defined what a planet actually is. Pluto, if you so will, was unlucky in falling through the grid by not fitting one of the three criteria. Case closed, get over it.
All that said, I am following the incoming data on the first TNO ever explored at relatively close range with high anticipation. This is already very interesting, and will become more so as New Horizons will continue sending the data being gathered during the Pluto encounter over the next two years.