Raymond, Mark, thanks for this work!

I'd include the following in the PEP (under the "from float"
discussion), what do you think?

"""
Update: The .from_float() method was added to Python 2.7 and 3.1
versions, providing lossless and exact conversion from float to Decimal 
(see issue 4796 [7]_ for further information).


It has the following syntax::

    Decimal.from_float(floatNumber)

where ``floatNumber`` is the float number origin of the construction.  
Example::

    >>> Decimal.from_float(1.1)
    Decimal('1.100000000000000088817841970012523233890533447265625')
"""