Google updated the App Engine roadmap this evening with huge news! XMPP, inbound / outbound email, and background tasks are coming to Google App Engine this year!
With these additions, a ton of new application possibilities open up! For example:
Instant Messaging, Real-Time Applications
XMPP opens the door to IM applications, and any applications that benefit from real-time updates (more so than just simple polling)
Micro-blogging, Email automatons
Inbound and outbound email opens the door to complete micro-blogging applications like Twitter and Jaiku as well as all sorts of email based automaton systems.
Game Simulation and Calendaring
Scheduled tasks and background processing open the door to persistent game state simulation, alerts, and calendaring. (for example… or maybe you just want to send reminders to pick up the milk)
Pretty cool stuff! Things are definitely going to heat up in 2009!