Using reference as class members for dependencies

I am going back to C++ after spending some time in memory-managed languages, and I'm suddently kinda lost as to what is the best way to implement dependency injection. (I am completely sold to DI because I found it to be the simplest way to make test-driven design very easy).

Now, browsing SO and google got me quite a number of opinions on the matter, and I'm a bit confused.

As an answer to this question, Dependency injection in C++ , someone suggested that you should not pass raw pointers around, even for dependency injection. I understand it is related to ownership of the objects.

Now, ownership of objects is also tackled (although not into enough details to my state ;) ) in the infamous google style guide : http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml#Smart_Pointers

So what I understand is that in order to make it clearer which object has ownership of which other objects, you should avoid passing raw pointers around. In particular, it seems to be against this kind of coding :

class Addict {
   // Something I depend on (hence, the Addict name. sorry.)
   Dependency * dependency_;
public:
   Addict(Dependency * dependency) : dependency_(dependency) {
   }
   ~Addict() {
     // Do NOT release dependency_, since it was injected and you don't own it !
   }
   void some_method() {
     dependency_->do_something();
   }
   // ... whatever ... 
};    

If Dependency is a pure virtual class (aka poor-man's-Interface ), then this code makes it easy to inject a mock version of the Dependency (using something like google mock).

The problem is, I don't really see the troubles I can get in with this kind of code, and why I should want to use anything else than raw pointers ! Is it that it