Notes from the April, 2006 meeting:

During the meeting the CWG was of the opinion that the “R() const” specialization would not match the const member function even if it were allowed and so classified the issue as NAD. Questions have been raised since the meeting, however, suggesting that the template argument in the partial specialization would, in fact, match the type of a const member function (see, for example, the very similar usage via typedefs in 11.4.2 [class.mfct] paragraph 9). The issue is thus being left open for renewed discussion at the next meeting.