I'm really confused why so few people have noticed Myghty. This Python web framework started as a direct Mason port, then added some MVC and advanced Resolver abilities (in the alpha release) that have turned it into an even more powerful web framework. The templating approach is already known and proven to scale for large deployment and development, as Amazon.com is using Mason.
While this particular code-base re-implementing Mason is young, it's running great and is quite solid. When I was looking for a Python web framework, I originally considered Cheetah, ZPT, and some of the other template designs but they all seemed deficient in some way compared to Mason which I had been using earlier. I'm currently using Myghty with SQLObject for a large production site at my company and the performance has been excellent, and being able to specify per Component Caching is a feature you won't want to live without in any templating language once you see it in operation.