How can I implement Comet / Server push in Google App Engine in Python?
We just announced the Channel API to do comet push with App Engine apps: http://googleappengine.blogspot.com/2010/05/app-engine-at-google-io-2010.html
If you're at Google IO, I'll be talking about this at 1pm tomorrow (on the APIs track): http://code.google.com/events/io/2010/sessions/building-real-time-apps-app-engine-feed-api.html
Here's the YouTube video of the session: http://www.youtube.com/watch?v=oMXe-xK0BWA
Hopefully last update! This is now released: code.google.com/appengine/docs/python/channel