As we all noticed from many examples posted in the past (especially by R0J0hound) dynamic lighting system is very possible to do in C2 and it's working quite effectively (high and steady fps with low cpu usage) Been using myself modified version of "mario_record_w_shadows.capx" with very large layout and high object count and never had any problems or slowdowns. Those files stated by eli0s even works nicely on mobiles.
And I will add a request from myself for official version of the light/shadow plugin.
I do not believe that this would be difficult task to do - at least not that difficult as multiplayer plugin
I could see it as a plugin, an object you add to layout that work as a light source. You could set color, cone angle, falloff, glow etc. And every object of that kind added to a layout would work as a separate light source, so you could have multiple lights scattered across the screen.
And then you will add a behavior (shadow caster) for every object you want to have shadows, again with few options to set. Like shadow opacity, shadow color...
R0J0hound is using imagepoints to define objects shadow border/area... But we already have polygonal collision masks with vertices - why this vertices can't be accessed and be used instead of image points?
But well. It's just a nice dream to have for now. But I do believe this is possible to do at this moment.