How to build an anonymouse.org clone on Google App Engine?

I like the simplicity of anonymouse.org but would like to build a free versio开发者_开发知识库n running on Google App Engine.

What would be required to do so?

Is it complicated to completely hide someone's location?

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Here is a quick guide to set up a proxy using Google App Engine.
The proxy server is based on Mirrorr, an open-source web caching project by Brett Slatkin

You can download the source code here.