[throwaway5752]

If so, I can imagine the Moon playing a role in that

It doesn't. The planet was spinning when it coalesced from a planetary nebula and conservation of angular momentum means it sped up as it coalesced. As the moon moves further away it _slows down_ the rotation of the planet.

[hawski]

I stay corrected on accepted theories.

I tried to find some discussion on this subject. I found this [1] quite recent paper (2016-03-31) that states that influence of Moon is necessary to maintain Earth's magnetosphere. Just food for thought. There are articles that quote this paper on the Web, but they have this suspicious date of 1st April (but paper was published day before) :)

[1] http://www.sciencedirect.com/science/article/pii/S0012821X16...