I decided to benchmark the app engines and see if it can live to the promises that google are making.
For the benchmark I used a simple web page that visits the google data store, retrieves some data from it (small data set, so that the test wouldn't be bandwidth limited) then converts it to JSON (not using any library code for that, ugly hand written string manipulation code).
The web page (actually the currently super useless supergtd app) was written in accordance to the sample provided in the google app engine documentation. My Python skills are so immature but I can tell that everything is pretty straightforward. Route is determined, correct python file loaded and my get method is run. The method internally calls the data store and retrieves data then does some string processing and sends the result back.
I tested from a server at softlayer (this one has the most bandwidth and the least latency of all the servers that I have access too, and it's a dual quad core monster for the records)
Here are the results from the benchmark (click for a bigger version):
Frankly, I am very satisfied by the results. The app engine was capable of handling any load I threw at it. Even though the request I am testing is kinda simplistic it manages to pass through enough different parts of the stack to make it relevant. Many APIs will have resources that are only slightly more complex than the sample resource I created for this benchmark.
Bottom line, top notch performance. And you don't even need to bother with your Elastic Computing Cloud configuration. You don't manage instances or anything (or even pay by them) you only pay per usage which is a much sweeter deal if you ask me (if your app does not require that you cross the sandbox boundaries that is). Oh and before I forget, serving static content was pretty fast too. Not breathtakingly fast but very decent to say the least (you should never skip proper client caching though, at least to save the bandwidth)
Did I mention that I need some Ruby love? Please.