You will notice buried in accounts of the recent killings of civilians in the Kandahar area a sentence or so about the Strategic Partnership Agreement. Talks have been going on for a long time. In fact a long article on the talks can be found dated June 13 2011 in the Guardian here
The U.S. is supposed to turn over security to Afghans in 2014 but that does not mean all U.S. troops will leave. There will be special forces remaining and trainers who may very well fight alongside Afghan security forces. The Strategic Partnership Agreement talks have been going on behind the scenes in secret with no attention being paid by the press or the public. The talk is all as if in 2014 it will be all over and the Afghans will look after themselves.
The problem with the recent rampage in the Kandahar area is that it may make it difficult for Karzai and the U.S. to complete negotiations. Karzai will probably demand that there be no special forces night raids. Now he may very well demand that any remaining U.S. forces be subject to Afghan law. That is a complete no no for the U.S. This is what kept Obama from reaching any agreement to keep troops in Iraq after the SOFA there expired. However the U.S. is working around that by hiring private contractors for security and other measures. No doubt the U.S. is facing the same issue in Afghanistan as it attempts to agree to terms of its presence after 2014. Of course the public is never informed about what is transpiring in these talks.