SmartPet is standalone addon that is in the compilation. You can find here but the latest couple version had some errors.
http://www.wowinterface.com/download...fo.php?id=4104
The only stable version was pre 2.4 version of smart pet. Hopefully a new version fixing 2.5.1 bug will be up soon.I currently have versio 2.5.1 disable cause of the errors.