I can produce PEP and patch if necessary.
Yes, a PEP, please! Jim Fulton has been asking for this for a long time too. His main requirement is that timestamp objects are small, both in memory and as pickles, because Zope keeps a lot of these around. They are currently represented either as long ints (with a little under 64 bits) or as 8-byte strings. A dedicated timestamp object could be smaller than that.
Your idea of a base type (which presumably standarizes at least one form of representation) sounds like a breakthrough that can help satisfy different other needs.
--Guido van Rossum (home page: http://www.python.org/~guido/)