It
is well-known that several regularization methods can work equally
well for the removal of ultraviolet divergences in the
stress-energy tensor of quantum fields in curved spacetime. Their
mutual relations are known, and discrepancies explained. This
formal structure of regularization schemes for quantum fields in
curved spacetime should remain intact when applied to the
regularization of the noise kernel in general curved spacetimes; it
is the meaning and relevance of regularization of the noise kernel
which is more of a concern (see comments below). Specific
considerations will of course enter for each method. But for the
methods employed so far, such as zeta-function, point separation,
dimensional, smeared-field, applied to simple cases (Casimir,
Einstein, thermal fields) there is no new inconsistency or
discrepancy.