A brief mention of some recent 3D developments. Been following the Alternativa engine development for a while and their blog shows some very interesting demos. At a glance, it seems to be optimized for interactive gaming, whereas PV3D is being developed for very general usage. I could be way off on that – just a quick observation 🙂 Check it out for yourself here.
Eduardo Dias da Costa pinged me about a 3D panoramic viewer, which you can see here. That’s it for now … back to work!
The Algorithmist 
I’m not sure your observation is that far off. In fact.. I haven’t seen that many comparative observations out there. I have not tried out Alternativa but I have seen the examples and it does seem to me that they’re trying to create 3D worlds whereas pv3d is heavy and is best used in a minimalistic way.
btw – more here, http://drawlogic.com/2008/04/17/as3-flash-3d-engine-alternativa-platform-drops-a-nuke-isometric-and-fps/