When you upgrade your Mac OSX from Leoprad to Snow Leopard, you are bound to encounter compatibility issues among your various applications. There is virtually no tool in Snow Leopard that can give you a report on whether such applications will work or not. But a separate program called Snow Checker does the trick.
Choose to have the program list all programs or just the 3rd party applications that you installed in your system and it will simply display all applications including its status whether it is compatible or not. This software is free by the way so give it a download.
I have never bothered studying Ruby nor Rails because of its ever confusing ways to even install it in your system, whether they be in Windows or Mac OS. Really. I managed to install part of it in Windows, and made a simple application but got stuck at a certain point where I gave up. When a friend of mine told me to study it because the Ruby industry is pretty big and can offer big cash driven development opportunities, I gave it another try to install it. This time in my Mac OSX.
I still had a hard time again. But voila! I read that Mac OS Leopard comes with Ruby and Rails. Even its previous version Tiger comes with it. So I guess I can start learning right away. But before that, just to make sure, update the following Ruby related technologies with the latest version. The following commands will do just the thing.
Those are it. Now you are ready to go and start learning Ruby and Rails.