legend markerscale not working

On Ubuntu 8.10 (Intrepid Ibex) I'm using matplotlib 0.98.3 and would
like to use the markerscale to make my legend points smaller (e.g.
0.6). However, it does not appear to be working. The following code:

plot(arange(0, 100, .1), cos(arange(0, 100, .1)), 'ro', markersize=20,

draws a legend that has markers the same size as the original plot. I
saw someone posted on September 24, and had a response from someone.
For some reason, the response was blank (at least as it appears in the
list archives), so I thought I'd send another message to see if anyone
had figured out what needs to be done to get markerscale working?