I think there is a connection there, actually. The HUP means that space cannot be infinitely continuous, as it is treated in GR, because to give meaning to such spatial precision would require so much energy that spacetime would curl up on itself at scales smaller than the Planck length. So the HUP seems to imply that GR will need some kind of coarse-graining to unify it with quantum mechanics. That would seem to involve quantizing the gravitational field, which many think will be done with a spin 2 particle called the graviton. Why that has eluded a consistent theory so far, I don't know-- maybe it isn't possible after all.