Helper & Rake task for SVG fallback usage & generation. Assumes Rails w/asset pipeline, your svgs are all in app/assets/images/vector, and imagemagick & optipng are installed.

assets_helper.rb

module AssetsHelper
  # SVG with PNG fallback for IE8.
  # Run rake app:svg_fallback to generate fallbacks
  def svg_image_tag source, *args
    options = args.extract_options!
    svg_class = options.fetch(:class, '')
    svg_class += ' svg'

    content = image_tag "vector/" + source, *args, options.merge(class: svg_class)
    content << "\n<!--[if lt IE 9]>\n".html_safe
    content << image_tag("vector/fallback/" + source.gsub('.svg', '.png'), *args, options)
    content << "\n<![endif]-->\n".html_safe
    content
  end
end

svg_fallback.rake

namespace :app do
  task :svg_fallback do
    desc "Create fallback images for SVGs in app/assets/vector"

    vector_dir = Rails.root.join(*%w{app assets images vector})
    fallback_dir = vector_dir.join('fallback')

    Dir[vector_dir.join('**/*.svg')].each do |path|
      path = Pathname.new(path)
      file = path.relative_path_from(vector_dir)
      destination = fallback_dir.join(file)
      FileUtils.mkdir_p destination.dirname

      destination = destination.to_s.gsub(".svg", ".png")

      puts "Converting #{file}"
      system "convert -background none #{path} #{destination}"

      puts "Optimising .png with optipng"
      system "optipng --quiet #{destination}"
    end
  end
end

.. also worth mentioning that we have CSS that hides .svg in IE8