With MacOSX backend, the following fails:

from pylab import *
plot([1, 2, 3])
text(1, 2, 'Hello', backgroundcolor = 'red')

This plots a nice red box but no text. It looks like the backgroundcolor is set as the foreground.
mpl version 1.4.3
backend: MacOSX
Works correctly with Qt4Agg and, as reported on mailinglist, works correctly with TkAgg