Hi,

I have recently been thinking in such a game. Unfortunately I have not found the spare time to do anything but thinking ;-)

Anyway, box2d (http://www.box2d.org) should be fine for the physics. In fact there are already some pinball games, indeed in flash, taking profit of that API.

What I thought it could be really great is if the canvas could be designed using SVG with, for example, Inkscape. Many of the physics parameters for controlling box2d could be embedded as node proporties in the SVG (slope, resistance, elasticity, spring, ...)

That way with only one engine, people would be able to design, emulate many different pinball machines.