Sorry, got carried away. ;-)
Shift 1: Convention over Configuration. Learning to let go of massive URL-mapping
patterns and declarations pointing classes at tables, etc. This is actually emotionally difficult for some folks.
Shift 2: Ability to modify the framework without re-writing the source. I "monkey-patch" Rails (and Ruby) on almost every project. I never do it by opening up the source code, but rather by mixing my changes into the framework (or language) at runtime. This is an enormously powerful shift that people tend to ignore at the beginning.
Shift 3: Testing, not debugging. I know of almost no Ruby/Rails programmers who use the debugger. Dave Thomas has famously said that he has NEVER used the debugger. Testing is where its at, baby.