In Pharo so far the Compiler compiled into instances of class CompiledMethod. Now, there might be the case that the result of the compiler (the compiledMethod) should not be an instance of the class CompiledMethod from the environment in which we compile, but from some other environment.
The Pharo compiler is now able to support that as Marcus explains here.
This is more flexible and should allow for cross compiling locally or into remote environments. One could use it to build up a new environment within the existing one, ...