No, ODE isn't multithreaded. But nVidia PhysX is based on multithreading, and also can be accelerated with nVidia physX capable video graphic cards. Otherwise the engine will use the CPU processing power, using multithreading obviously.
It's the most advanced physics engine in the world by now, I think.
Also note that is free for commercial and non-commercial use (just have to pay for the source code of the SDK, but the non-source code version (bin) is completely free).