In Gtk2SVG version 0.1.1 an ellipse can now be rendered

#!/usr/bin/env ruby

# file: draw3.rb

require 'gtk2svg'


s =<<SVG
<svg width="400" height="110">
   <ellipse cx="200" cy="80" rx="100" ry="50" style="fill:yellow;stroke:purple;stroke-width:2" />
</svg>
SVG

a = Gtk2SVG::Render.new(s).to_a

area = Gtk::DrawingArea.new

area.signal_connect("expose_event") do

  drawing = Gtk2SVG::DrawingInstructions.new area
  drawing.render a

end

Gtk::Window.new.add(area).show_all
Gtk.main

Screenshot

Screenshot of the GTK2 application rendering an ellipse