Papervision3D is an open source 3D engine for Flash ActionScript that was recently released in public beta. This special tool makes it possible for Flash developers to render interactive 3D objects in realtime using the Papervision3D engine. It is worth mentioning that this is not another Swift3D, the standalone 3D modeling and rendering tool for creating flash-friendly 3D animations. Animations made in Swift3D are rendered beforehand and are merely imported into Flash as video or framed animation. 3D objects illustrated in the Papervision3D samples are true 3D objects that are rendered in the Flash player itself.
Some old yet impressive samples of the engine in development that could be seen here show the potential of this engine for creating interactive 3D movies. You can watch the new video showreel here and then check out the details for trying Papervision3D for yourself from the recent announcement post.