Meaning of = delete after function declaration

Deleting a function is a C++11 feature:

The common idiom of "prohibiting copying" can now be expressed directly:

class X {
    // ...
    X& operator=(const X&) = delete;  // Disallow copying
    X(const X&) = delete;
};

[...]

The "delete" mechanism can be used for any function. For example, we can eliminate an undesired conversion like this:

struct Z {
    // ...

    Z(long long);     // can initialize with a long long      
    Z(long) = delete; // but not anything less
};

1. = 0 means that a function is pure virtual and you cannot instantiate an object from this class. You need to derive from it and implement this method
2. = delete means that the compiler will not generate those constructors for you. AFAIK this is only allowed on copy constructor and assignment operator. But I am not too good at the upcoming standard.