title: OS-X support for std::tr1
body: <p>What is the current support for tr1 or the new C++0x on the Mac</p>
  
  <p>I know that the gcc supplied with XCode is always a couple of versions behind that available from gcc.gnu.org so I was just wondering what the state of play for modern support was.</p>
  
  <p>For example do I need to download boost to use shared_ptr or can I get it from std::tr1?</p>