OpenSocial with Java
Though I wasn't able to release an app this weekend, nonetheless Weekend Apps - Opensocial was a great experience. For those that know nothing of the technology theme, Weekend Apps is an efficent way to get weeks of experience in a weekend having industry experts there to help you through problems.
One of the "a-ha" moments for me was learning that OpenSocial gadgets can run arbitrary html and thus can have embedded applets (as they already support embedded flash). For a user with Java 6 installed, the ability to drag the gadget outside the OpenSocial container and continue to run it after leaving the page might make for a killer app.
I was able to very quickly get a draggable gadget working using sample code from Sun. Code here
The only caveat is that because applets autostart, some care needs to be taken to handle things if the user minimizes a gadget then expands it. One might have the landing page be a static image of the app that the user would have to click to run it.
