Quote Originally Posted by abrojtm
Shinra in FFX-2 makes mention of taking out the planet's life and using it for energy. This is a reference to FFVII, but it is unknown whether or not they are directly correlated. Hey, perhaps the Al Bhed are really the Ancients.
There's no actual correlation; it's just a reference. Here's something interesting, though: in FFVII, if you watch the TV in the basement of 7th Heaven, you can see a report on the screen. The header proclaims "SIN" and the reporter looks suspiciously like an Al Bhed.

Again, however, let me restate that there is no direct connection between those or any other FF's.