Google Friend Connect

Google Friend Connect provides social networking interfaces , social gadgets and Api. Only the Conversation element here on  Google Web Elements works with Google sites. 

Friend Connect Gadgets:
As Javascript is used in the friend connect gadgets. I'm sure more Google Friend Connect Gadgets will be available in future.

Google Sites Suggestion Gadget:

To create this Google Sites Suggestions ' conversation element' (subject commenting gadget)

Firstly you will need a Google account and then sign up to Google Friend Connect.

Once you signed up for Friend Connect. You can customize the conversation element at Google Web Elements.

You will be prompted to upload 2 files rpc_relay.html and canvas.html

Then embed the generated code. If you are not signed up for Google friend connect It will not work.

The 'conversation element' is physically stored on, not on your Google Site. So an iFrame is used for the URL.
IFrame Example: 

<iFrame src=";topic=Google%20Sites%20Suggestions"></iFrame>

Gadget Example:

More Friend Connect Gadgets:

Google Friend Connect API:

Google Web Elements: