So I have this idea to utilize Google App Engine as a multiplayer game lobby. Flash games tend to peak high upon the very first days of the release. As there are quotas for free service I had to run some tests to get an idea what to expect. At this time I am using memcache as a game server registrar. The registration was set to expire within 1 minute. I prepared a stressor program to issue game server registrations an a continuous loop.
In 12 hours I had issued about 40000 game server registrations. It seems the CPU time is quite high. The average response time was also 22 seconds. Now I need to implement the logic that a game would first try to connect another game before promoting itself as a server.
Update: You can use a naked domain with google app engine with an URL redirect.