Not with certainty. If PEP 397 is accepted soon enough, then it will be Python 3.3, as there are no planned 2.x feature releases. If the PEP is accepted but too late for 3.3, then it would be 3.4.
The launcher itself is independent of Python, of course. The work required (assuming the PEP is accepted) is to integrate the code and tests into the CPython repo, and then integrate the launcher into the Python installer. As this is not an in-Python feature, in theory it could be added to Python 3.3 even after the first beta release; but that will depend on the release manager.