Yesterday at the free "Flash Day" at the Unity Unite conference, the Unity team showed off their new Unity -> Flash Stage 3D converter. The product exactly what it sounds like it does: it converts 3D games built in Unity to "Molehill" compatible Stage 3D of the type supported by Adobe Flash CS5.5
The Unity team demo'd a game built in Unity that was converted, fairly quickly to a .swf. that played, pretty much the same game as that could be targeted to any of the current Unity platforms. As well as a .swf, a .swc is produced that provides an API so the Flash can communicate with the Unity produced code, and vice versa. As well, the Unity team suggested that they could provided full source (.fla, .as) of the exported game.
There were a few things missing right now (i.e Unity networking support), but for the most part, the product looked quite impressive.