Right now, we don't support the Whatsapp button. That button only support mobile environments and, while it may be gaining traction, the data that it's more popular than Twitter is tenuous.
If you have any information on how you'd like to use Whatsapp within JFBConnect and what benefit it'd provide, we'd love to hear it. We're always adding new features to JFBConnect and this may be something we add in the future, but right now, it's not one of our main investigation points.
I hope that helps,
Alex