Yeah, it's not the wishbone, but it did evolve out of the wishbone. That was what they ran at GSU when Russell and CPJ decided to move the backs up to the line so they could pass better. CPJ explains:
http://www.youtube.com/watch?v=MSR3Y-yl1iQ
They realized that while in this formation,
they were still able to run the same option run plays that they loved running out of the wishbone.
With a little motion, you can see how similiar they are at the snap.
Here you can see how the same Triple Option is run out of the Wishbone,
and here the Flexbone.
The only difference is the playside back, who is the lead blocker, is now up near the line instead of coming out of the backfield.
The Flexbone is essentially the base Run and Shoot formation. So this obviously allows you to run pass plays that the Wishbone doesn't. So it gives you the run offense of the Wishbone with the pass offense of the Run and Shoot. I don't think you can say it's one of the other. Just like CPJ says in the video, it's a combination of a couple different offenses. This is probably why he doesn't call it a "bone", he calls it a Spread because the Run and Shoot is the original Spread. Hopefully this helps some folks and I'm not screwing it all up.