The IAB guideline for RIA Ad Measurement have been released in draft form.
From the summary:
The guidelines state that “In instances where significant user activity (click through and responding to mail, changing search options through clicking or typing, etc.) is present, this activity can be directly tied to ad-serving and counting provided that counting rules are defined in a consistent and fully disclosed manner.” The guidelines go on to acknowledge that, “In special circumstances, due to the nature of the application, there may be no material user activity, for example, a single streaming event (e.g., financial tickers, sports game coverage, long single-stream video content).” For these types of environments, currently accepted auto-refresh guidelines should be applied including the consideration of user-set auto-refresh and for site-set rates, an assessment for reasonableness based on the rate and nature of the content as well as materiality.
You can download the draft guidelines here.