I finally took the dive into the Google App Engine last week. It's free to get started (up to 10 applications per Google account) and gets my feet wet for this whole "cloud computing" crapfest. Here are my first impressions of Google App Engine and Python. I won't go into my issues with cloud computing in general and all the hype surrounding it, and how it will magically solve all of our scalability and maintenance issues.
I was surprised at how well done the Google App Engine is, and how quickly I could get started. Downloading and installing the local development environment was quick and painless, and walking through the tutorial, I had a very basic "guest book" application written and deployed out in the vast Google cloud for the world to see. The local development server was up and running within minutes of downloading and installing, and making changes to the Python scripts didn't require any redeployment or restarts. Uploading to the Google servers was a matter of running a single script and entering your user id and password. There is even an admin console where you can see stats on your page visits, bandwidth used, performance, etc.
I like that the Google users and authentication is pretty much built in, as well as the simple "webapp" MVC framework, and that you can use any pure Python library or framework you want to use (as long as there aren't any extensions written in C). The data access layer and GQL query language is interesting -- one big free-form data store where you aren't dealing with individual tables so much as just defining your entities in your code's data structures, and reading and writing from them as if they are tables.
For now, the only supported language is Python, which I have never dealt with. That really wasn't much of a hurdle since the syntax is pretty straight forward and easy to learn. I wouldn't mind seeing other languages supported in GAE, though not sure it really matters or if it is worth Google's time, money, and effort to expand support to other languages. I'm sure if they asked 100 developers they would get 100 different answers of what languages should be supported.
I'm a little more ambivalent toward Python. I didn't dislike it, but it just didn't grab me by the balls and make me exclaim it's superiority either. I can say I'm not a fan of the whole "indentation exception" crap. As a guy with more of a C and Java background, I like my curly brackets instead of relying on indentation levels, which remind me too much of COBOL, yuck!
Anyway, here's my trivial little application. It's all "tutorial-ware", straight out of the book with a few CSS enhancements and a simple "about" page. It's not useful, but not bad considering how little time it took to write.
Next step.... write something useful. I definitely want to get into this more and add it to my development toolbox.