My pleasure Jon!... I heard several interesting things done with the Raspberry Pi, only too happy the donation is being channeled there... and for furthering your WP plugin dev work.
As for further testing the plugin, here's something to look at:
http://theastrologer.com/waptm/blog.php
We're working on smoothing the rough edges and figuring out issues with this approach. Seems like a truly workable solution, at least within the limits of the iframe approach.
One issue we found was that the plugin's cookie does not apply to /category pages. If you go to http://theastro.staging.wpengine.com/?theme=2012 and click on "Daily Overview" under each post, you'll this in effect. But if we manually add the ?theme=2012 string at the end of the /category page's URL, it works. Any clue?