Just my two sense but at college/uni many of my proffessors encourged us to do this:

Code:
using std::cout;
using std::endl;

   cout << "Hello World!" << endl;
Rather than:

Code:
std::cout << "Hello World!" << std::endl;
Just the way I was taught, and as that is how I have been coding I would never use the std:: prefix against the using declarations. But I do see the point in it as for one it can reduce having to type all the using declarations under the header file eg:

Code:
#include <iostream>

using std::cout;
using std::endl;

#include <string>

using std::string;
using std::getline;
But like I said I was taught this was the better thing to do, and that is the practice I have followed since. But I do agree at the end of the day this is totally a style issue over a programming essential. What I do see more rarely is

Code:
using namespace std'
begin used as a short cut. At least the using decllarations show at least some effort on the coding side. Even large industiral console programs to do not use the above anymore. It is good to see it is a practice dying out.