With the new release there's a file to edit for snap to grid.

File /usr/share/hildon-desktop/transitions.ini has a line named snap_grid_size = 4 around line number 182. Edit the value bigger to have more notiacable effect of snapping. I have it on 8 currently and it works pretty well. Though still no snapping to same line as nearest objects, only makes it easier to put icons on same level.