Last week, Google finally released the Channel API [1, 2] for Google App Engine. It has been available to developers for six months , but not on actual app engine for production. I had built a few video conferencing and text chat applications [4, 5] using Flash VideoIO project  on Google App Engine. Earlier, I had to use Ajax/polling technique to get events related to chat and user list. In the last couple of days, I modified those applications to use the asynchronous event notifications using the Channel API. More text from  follows:
"Random-Face : This is a chatroulette-type application built using the Flash VideoIO component on Adobe Stratus service and Python-based Google App Engine. ... You can view the source code of two files, index.html that renders the front end user interface and main.py that forms the back-end service."