The Beal, Granville, Tijdeman-Zagier Conjecture, i.e.

If $A^x+B^y=C^z$ , where $A, B, C, x, y,z$ are positive integers and $x,
y$ and $z$ are all greater than $2$, then $A, B$ and $C$ must have a common prime
factor.

... and its associated [$1,000,000 prize][1] for proof or disproof seems to have gone largely unnoticed in the mathematics community. Please answer with (A) references to past or ongoing research or (B) references to equivalent forms of this conjecture known prior to Andrew Beal posing it in 1993.

[1]: http://ns3.ams.org/bealprize.html