For security reasons, IFrame usage is restricted in newer versions of Jive. It may be allowed if wrapped in "safe mode" as briefly explained by Thomas Jung during the call mentioned in the discussion here:
This is also covered in a bit more detail in the JiveX documentation here:
Managing HTML Widget Security
In safe mode, you can still call the assets associated with the core Jive installation as follows: <script src="/resources/scripts/jquery/jquery.js"></script> <link rel="stylesheet" href="/styles/jive.css" media="all">
Widget upload access should be limited to users you trust. Because any social group owner can upload resources to these widgets, it's possible for users to make incorrect judgments about appropriateness and security, so make sure group owners are carefully chosen.
Let me know if you had any other questions on this.