time_zone_model.rb

  class TimeZoneModel
    class ZoneProxy
      attr_reader :target

      def initialize target
        @target = target
      end

      def name
        @target.tzinfo.identifier
      end

      def to_s
        @target.to_s
      end

      def <=> other
        target <=> other
      end
    end

    def self.all
      @all ||= ActiveSupport::TimeZone.all.map do |zone|
        ZoneProxy.new(zone)
      end
    end
  end

usage.erb

time_zone_select(object, :method, /(America|Canada)/, :model => TimeZoneModel)