When I connect to the 2011 endpoint of the Core Service on a 2013SP1 machine and request the API version I get 7.1.0 where I expected 6.1.0. That suggests it is not the API version but the Tridion version; is that intended and correct behaviour?
Same applies to the 2012 endpoint on the same machine (where I would expect an API version of 7.0.0).