http://opende.sourceforge.net/
It is also released under the GPL. I have seen some videos and I was really impressed about the physics this engine has like seen on this video:
http://de.youtube.com/watch?v=21Hucteare4
I would like to know you think about that. I think to port/compile WZ running with ODE will be a lot of work and I think maybe a lot of new software will be needed for replacement of the original World Edit/Pie Edit etc.
Furthermore, using ODE will have WZ to need higher hardware specs due to its complexity and I think every single script in the recent WZ might have to be translated to work with ODE.
In my opinion I go with the original GFX engine. Even if it has its restrictions with polygons and texture sizes. As I don't have a computer where I can use a higher resolutions than 1024x768 @ 32bit.
Anyway the ODE looks good in my opinion an I think it schouldn't have too much problems with moving about 500 or 1000 tanks on a map if the models are small enough. And due to the physics it schould look more realistic when tanks explode or just destroying buildings could be a bit more complex, like "single stones" or parts of walls flying everywhere.

