What is the license for the decimal module, and is said license compatible with the BSD license that Django uses?

It is the the same license as Python itself: http://www.python.org/psf/license/

Are the authors of the decimal module OK with usdistributing it with Django?

You don't need my okay, but you've got it anyway. Per the source file, the listed authors are: # Written by Eric Price <eprice at tjhsst.edu> # and Facundo Batista <facundo at taniquetil.com.ar> # and Raymond Hettinger <python at rcn.com> # and Aahz <aahz at pobox.com> # and Tim Peters