Google Moderator has been Dropped. Google+ Community post can also be embedded on Google Sites. You can post a Quick Survey with Comments,an image, Image Galleries , Web Sites etc... through Google+ Personal Profiles, Collections, Business Pages and Communities.
Have a look at the New Goopal - Google Sites Community. Everybody is free to Join & Contribute. Subscribe to our YouTube Channel for more Live content for the Community.
The Google Moderator System allows you to embed a Forum into your Google Site.
Ideas can be submitted and voted on.
Google Moderator iFrame
Use the full URL in an iFrame
You will need to be signed in to your Google Account.