Matthew Perry has a good article entitled When Journaling Helps Your Preaching (4 July 2008). I don’t use a Moleskine myself, but I have found handwriting study notes and sermon drafts extremely helpful in my own preparation for preaching, and my own personal meditations. I find scraps of A5-sized paper useful as they are about Bible size, and easily accommodate my habit of writing in short bursts that need finishing later, sometimes with something different in between.
It is always an encouragement to see that you’re not alone in your preferences for writing over typing as the first draft. Not having Matthew’s good handwriting, I tend to type up my ramblings, and I find the second go over them helpful in retaining the material, though I find I always have much more material this way than is practical to incorporate into a sermon. Occasionally such ‘discarded’ material makes its way into the blog.