Arranging Windows sticky notes option already exists in Notezilla .
To automatically arrange desktop sticky notes, right click on Notezilla icon in taskbar and choose Desktop Notes->Arrange Notes.
Watch this video for more clarity:
Inside memo board too this is possible. Go to Notes Browser, select a memo board, right click inside a memo board (bottom view) to arrange notes.
The distance between sticky notes is measured based on the size of each sticky note. And also, based on other components like note toolbar, scrollbar, find bar etc.