Electric field within conductor

[Fluxxx]

How come there's no electric field inside a metal cylinder, even though there's positive charge on side and negative charge on the other? For example look at this picture:

As you can see there's is a zero electric field within the cylinder. Why isn't there an electric field that's directed from the + charges within the cylinder to the - charges within it?

 

[TESL@]

The charges move freely to screen the field, two fields cancel each other.

 

[rumborak]

The original outside field still penetrates the sphere. It's just that the charges inside the sphere move around and build up a counter-field that exactly cancels that outside field. So, it's the net field that is zero.