My have some objects that move pretty fast, and when they do, they sometimes go right through other colliders instead of bouncing off like they should. I thought that was supposed to be fixed with Unity 3. Is that incorrect?
fast moving objects should also raycast for collisions in unity3d < 3.0.
This is no bug it is just a calculation matter with the number of update cycles per second. More update Cycles == less collision pass throughs == mor computation power.
In unity 3.0 you can activated ccd (continous collision detection) which consums more calculation time, so only use it for few objects when it is necessary.