Hi help(plot) states something like

    > [...] If you make multiple lines with one plot
    > command, the kwargs apply to all those lines, eg plot(x1,
    > y1, x2, y2, antialising=False) Neither line will be
    > antialiased. [...]

    > but the MPL manual says "antialiased" and "aa"
    > respectively, which works. "antialising" gives

    > TypeError: There is no line property "antialising"

    > However, if I set antialising to False in .matplotlibrc or
    > try

    > plot(...,aa=False)

    > nothing happens. The plot is still antialised.

Hmm, you've found two bugs here. First, the docstring is incorrect:
"antialiasing" should read "antialiased". Note you can use the set
command to get the real information, since it actually inspects the
object methods

  >>> line = plot([1,2,3])
  >>> set(line)

The second bug is that agg is ignoring the aa property. I recently
refactored graphics context property handling in agg and forgot to
call the gc._set_antialiased method in the constructor in
_backend_agg.cpp. This is fixed in CVS.

While I was poking around I also found another bug! In interactive
mode with the TkAgg backend, the draw operation is being called twice
with each plot, halving the performance. Since tk is already pokey,
this is a problem -- and fortunately should be a relatively easy fix.

If you put a print statement in matplotlib.figure.Figure.draw, and
then set interactive : True and backend :TkAgg and fire up a standard
python shell and do

  >>> from pylab import plot
  >>> plot([1,2,3])

You'll see that draw is called twice. We've had a devil of a time
getting the tk stuff just right in backend_tkagg -- it seems like the
same bugs keep recurring in different guises.

We should be able to get this sorted out for a bug-fix release in the
near future, probably next week.