Cheetah 3d 5.1 came out yesterday, a less than two months after 5.0 came out. While it doesn’t complete the planned 5.x feature set (normal maps, more up-to-date FBX support, and particles are among the promised outstanding features) it represents a substantial improvement over 5.0.
In particular, the biggest single problem with the animation system (the inability to move keyframes on more than one object at a time) has been fixed (you can now move all keyframes down a hierarchy from the current selection), and automatic vertex weighting has been updated to support heat-mapping (the same algorithm implemented in Blender 2.46), which is just ridiculously nice.