import math

width, height = 400, 300

size(width, height)
speed(8)

def setup():
    global frame
    frame = 1
    global dots
    dots = [[50*x + 25, 50*y + 25, (y - x)*10.0] for x in xrange(8) for y in xrange(6)]

def stepDots():
    global dots
    for d in dots:
        d[2] += (d[0] + d[1])*0.01

def draw():
    global frame
    global distort
    global dots
    
    stepDots()
    nofill()
    strokewidth(5)
    colormode(HSB)
    for d in dots:
        push()
        rotate(d[2])
        h = math.sin(math.radians(d[2])/5.0)*20.0
        stroke(math.sin(h)*0.1 + (math.sin(frame/48.0)*0.4 + 0.5), 0.7, 0.5, 1 - abs(h/15.0))
        scale(h/1.3)
        #rect(d[0], d[1], 10, 10)
        arrow(d[0], d[1], 20)
        pop()
    
    frame += 1

I was just asked how I did this
http://www.vimeo.com/clip:218013
so here goes ...

NodeBox test: arrows

Python