Honest feed back? How about this version:

  def fact(max=ARGV[0].to_i, i1=1, i2=1, i=1)
    i < max ? fact(max, i2, i1+i2, i+1) : (puts i1)
  end 
  fact()

This was the 2nd program I wrote in Ruby (I know it's recursive and therefore inefficient but my goal was to see how short I could make it not how efficient)