I've posted another set of patches for date/time types. They fix arcane
problems with BC dates; if you don't use them very often then you may
not want to bother patching at this time. The fixes are in the
development tree for the next release.
Look in ftp://postgresql.org/pub/patches/dt-2.patches.
From the top of the patch file:
These patches allow BC dates for the date data type,
and fix a behavior that two-digit BC dates were adjusted
by two millenia!
- Tom