Well, even if Appcelerator does expose some of the specifics of Google’s App Engine platform, there has already been a first pass at hacking up a port of the App Engine API to Amazon’s EC2 platform that is already up and running at AppDrop. It seem highly likely to me this new open source project will get decent support from the OSS community and that more hosts will be offering App Engine compatible platforms, so I figure on trying out Appcelerator and App Engine as soon as I actually need a website to go along with my game.
I’ve already got a fair investment in a web site, which has never been publicly deployed, written against Pylons. At this point a first pass at getting Pylons working against App Engine has be completed by Ian Bicking, so probably the second thing (after getting familiar with Appcelerator) I’ll have to have a look at when a website becomes necessary is if Appcelerator will integrate with Pylons in anyway, shape, or form. Pylons is a let-you-replace-what-ever-you-want type of light weight framework, so I’m not to worried about it being the blocking one of the pair.
Update: Mark Luffel one, of the Appcelerator devs, just commented that “We’ll have a version of Appcelerator+Pylons+AppEngine soon, but glueing those three together shouldn’t be hard…” and that is most excellent news!
Josh Heitzman on Codecrafting 
Hey Josh,
Pylons is actually the default framework for using Appcelerator with Python. The new App Engine integration doesn’t use Pylons only because Mr Bicking’s work on sandboxing Pylons wasn’t complete when we ported to the App Engine. We’ll have a version of Appcelerator+Pylons+AppEngine soon, but glueing those three together shouldn’t be hard if you’re interested.
The important changes between the “python” and “appengine” backends in Appcelerator are that:
1) “appcelerator/core.py” has been tweaked and moved to the projcet root at “appcelerator.py”
2) services are scanned for in the “app/services” directory, rather than in “your_project_name/services”
I hope this gets you started, when you have time, please post your progress (or questions) on the Developer Network, I’m interested in seeing how this goes.
–Mark