Specifying Rails version when creating an application
As I've started working on multiple Rails apps on my machine, and using different Rails versions across applications, I've ended up with different versions of Rails installed. I've discovered a simple way to specify the Rails versions needed for an application when creating the application.
Format your command like this:
$ rails _3.0.9_ new testapp
This will, for example create a new Rails app named 'testapp' with the Rails version of 3.0.9. You can verify by running $rails -v in the application root.