Actually, it is Apple's problem. If software that works on 10.4/10.5 doesn't work on 10.6, that means Apple can't even maintain compatibility between their OS releases. That is Apple's problem. They (and you) have to wait for developers to port their apps to 10.6.
It would be a lot easier if Apple just made Snow Leopard compatible with 10.5 apps.
And, the nicer interpretation is that Snow Leopard is simply full of bugs. ("My God, It's full of bugs!")