I install the v1.0.1 Optimizely Wordpress Plugin and in the settings it says
Optimizely project code
You can find your project code on your project's experiments page. Go to optimizely.com/experiments, make sure you've selected the right project and click on <Project Code>, then click on 'Copy to Clipboard'. You can then paste the code in the box below. Your project code should start with "<script" and end with "</script>".
It would be nice if that was updated to reflect the current location to retrieve the project code: My Web Projects, Settings, Implementation.