[gojomo]

Sounds nice, but I'm not sure it's the only way -- that Heroku 'essentially needs to build all of that'. It'd be interesting to see whose routing-to-instance is faster in the non-contended case, between Heroku and GAE. Do you know of any benchmarks?

[nikcub]

Don't know of any benchmarks, but I have/had a number of projects on AppEngine and it is very good (but expensive). I would be looking to include Elastic Beanstalk in a comparison as well, as it is gaining popularity since it launched (it doesn't have the lockin and supports any environment).