I was trying this out when Unity announced their Flash contest. So I submitted a proto for the contest. Flash export is still in Beta, but it's pretty good.
Here's link to Flash screenshots
Link to playable flash version (no sounds, lights and I couldn't put any cool shaders)
I'm actually amazed at the complexity of Unity to Flash publishing - it converts all C# code (.NET / Mono framework) to Actionscript 3. What's more frakking mazin? Unity engine itself occupied under 2.5MB for all this!! (all this means - rendering, physics, collision, particle-systems, audio and more)