Hi Bruce,
Sorry it took so long to get back to you. I'm usually better than this. I just have a few meatspace things I need to deal with, so I've been a little out of commission for a week or so.
The Java implementation was an experiment, one that will probably be abandoned. Right now, Python is our only supported server installation. For the upcoming release of 2.1, I'm reworking the architecture to be a bit more flexible, extensible, and modularised. Because of that (and for cost reasons), we'll be moving our main server to a NodeJS powered server we host ourselves. Support for App Engine may come at a later date, but it isn't the top priority. We realise that there are people who have set up App Engine servers who want to be able to self-host and use the updated software-- we're working to make it as easy as possible to self-host the NodeJS implementation. We're looking into offering a hosting solution, in which we set up the server for you, monitor it, but don't have access to any of the data. We're looking at charging $20/month for something like that.
I hope I answered your question. Thanks for using the project, and let me know if there's anything you need or anything I can do to help.
Thanks,
Paddy