I have written a small patch which extends the functionality of
Figure.legend and pyplot.figlegend to match that of Axes.legend.
This patch allows figlegend to automatically build a legend for lines
with the "label" property set when figlegend is called without a list of
strings or object handles.
Also, the "loc" argument is made optional, and defaults to the upper
right, same as Axes.legend.
I hope the attached patch is suitable for inclusion. I have also
attached a test script showing each of the call signatures.