Probably one of the most visible changes is that Gemfile and Gemfile.lock will cease to exist. Well, under that name, at least. Enter gems.rb and gems.locked.

Fand ich erst komisch, aber die Erklärung ergibt natürlich Sinn:

In general, on UNIX-ish systems, .lock stands for a very specific type of file, a, you might have guessed it, lock. They are used all over the place for expressing locks on system resources and thus this Gemfile.lock thing is more confusing than helping. Specifically, locks are usually treated as temporary files and thus could be, under certain circumstances cleaned up by careless scripts.

Da wird es eine saubere Transition geben, man muss sich also keine Sorgen machen. Es wird bei Ruby-Einsteigern (mit älterer Lektüre), aber garantiert für etwas Verwirrung sorgen. :)