Calculating simulated motion blurring

I writing a small game with rubygame. Use fixed framerate (30 f/s) with
Rubygame::Clock’s tick method. While experimenting with sprite code, I
found that objects appear (on the screen) to move more smoothly if I
simulate “motion blurring” http://en.wikipedia.org/wiki/Motion_blur. I
was wondering if there are any ruby modules out there to help with the
calculating of the positioning of the latent images for maximum
realism/smoothness, as Rubygame doesn’t have anything built in.