I cannot wait to see Corona Scatter improvements too.
There were times when Corona Team was sneak peaking "Scatter Pro", although looks like the plans for this have died.
Here's what I wrote 2 years ago and it's still valid in terms of the features I'd love to have:
"If only it had control over the scale of each separate scattered object (within instanced objects menu), simple exclude include with option to mark the areas with a brush, and option to save your setups, it would be a perfect tool.
Using distance maps and advanced scattering techniques unfortunately also slows Corona Scatter down a lot."
Additional handy features would be:
-being able to easily select object in scene from CScatter Objects menu (i.e. right click->select object in scene)
-clustering
-edge trimming