Details on Google App Engine's caching proxy?

Question

Google App Engine must have some sort of reverse caching proxy because when I set the response header Cache-Control public, max-age=300 from one of my servlets, subsequent requests to the app engine show up in the logs like this: /testcaching 204 1ms 0cpu_ms 49kb, whereas non-cached requests show up in the logs as: /testcaching 200 61ms 77cpu_ms 49kb.

Anyways, my question is: Does anyone have any more details about this reverse caching proxy?

Answer 1

Some of the details it would be nice to have answers for:

http://code.google.com/p/googleappengine/issues/detail?id=2258#c3