I'm integrating Omniture with a (very poorly done) web chat system. The solution involves their iframe pointing at their domain sitting on our site which creates a popup for the chat session. The popup contains an iframe pointing at our site with parameters passed into the querystring. My code reads the querystring parameters and inserts the analytics beacon. Iframeception. Apparently it's not possible to do this in any remotely sane way, according to the guy I'm dealing with anyway.
Amazingly it actually works. Even in IE. Without any frigging around with P3P headers. It seems IE sends the cookies in the header for third-party cookies if they were set earlier in the session, so it's all okay. I was surprised.