Proposed resolution:

Ammend in both:
[istreambuf.iterator]
[istreambuf.iterator::equal]

bool equal(const istreambuf_iterator& b) const;

[ 2009-11-02 Howard adds: ]

Set to Tentatively Ready after 5 positive votes on c++std-lib.

[ The proposed wording is consistent with 110 with status TC1. ]

The equal member function of istreambuf_iterator is declared const, but takes its argument by non-const reference.

This is not compatible with the operator== free function overload, which is defined in terms of calling equal yet takes both arguments by reference to const.