Setting a background on the annotation covers the arrow also. This didn't happen in 1.4.2. I've been using it to separate the text from any plot data points in cases where they overlap. Resolvable for now by redrawing an empty annotation with an arrow.

Pre 1.4.2:

Current:

Example code:

import matplotlib.pyplot as plt
import numpy
a = numpy.zeros(100)
a[::2] = 1
plt.figure(figsize=(5.9,4.4))
plt.plot(a)
shared_args = {"xytext":(-15,0), "va":'center', "ha":"right", "textcoords":'offset points', "arrowprops":{"arrowstyle": "->"}}
plt.annotate("Test", xy=(20,0.5), **shared_args)
plt.annotate("Test", xy=(20,0.4), backgroundcolor="w", **shared_args)
plt.show()

And the actual introducing commit, in the middle of what appears to be other restructuring 9d1c876