To be or not to be, that is the question! Or rather, to b or not to b! Because it's anybody's guess: does Fomalhaut b really exist?
Approximately 25 light years away, this exoplanet (in the constellation Piscis Austrinus) remains ... unconfirmed. The real question is: if we found it, why is it unconfirmed?
Scientists inferred the existence based on its influence on the Fomalhaut dust belt which was not centered on a star - thus implying that it must be centered on something else, like a planet. Then they took a picture of it with the Hubble space telescope.
But something was wrong. It's orbit. Because of the dust disk, the planet's orbit would need to be elliptical, but if this were the case, the dust belt would be disrupted because of the estimated size of the planet. Could there be another planet in the mix?
Ray Jayawardhana argued that the misstep in the planet's orbit suggests that it might not be a planet at all and is pushing to have the exoplanet un-categorized as an exoplanet.
At very least, we know that something is there. The not-yet-confirmed exoplanet would likely be a similar size to Jupiter, and surrounded by a belt of dust. From Formalhaut b, its star would look about like what the sun looks like from Saturn.
In conclusion, I think it's a planet, so that probably pretty much solves the whole issue.
Pictures from NASA and this article.