こんなの書くとか

jquery.version.js

$.extend({
  version:function() {
    var v = $($().jquery.split(".")).map(function(){ return parseInt(this,10);})
    return {
      major:v[0],
      minor:v[1],
      revision:v[2]
    }
  },
  isOldVersion:function(major, minor, revision) {
    
    var v = $.version();
    var a = v.major * 100 * 1000 + v.minor * 1000 + v.revision
    var b = major * 100 * 1000 + minor * 1000 + revision
    return a < b;
  }
});