I'm sorry to reanimate this corpse, but... I've got the exact opposite request 
In other words, unlike @pled, I usually add to my notes at the bottom, because many (granted, not all) of them are going to be shared as PDFs to other people, and, naturally enough, they expect the text to go from the top to the bottom (i.e. newest things at the end). While for some things I agree that having the cursor always at the top is a good idea (I'm thinking of things such as technical changelogs), for more typical, non-technical usage it's more common to put the newest things at the bottom...
So, ideally, I guess that this ought to be a toggle somewhere on the preferences, as suggested elsewhere.