This sounds very interesting. I’m using MAMP to run a development install locally, and am having trouble getting this to work. I don’t get a preview, only the raw HTML/PHP code when i try to preview the template files.
I probably need to tweak the rewrite rules, but I’m not “fluent in rewrite” 
Here’s my setup, can anyone guide me in getting this to work?
Coda site is set up this way:
Root URL: http:///Applications/MAMP/htdocs/thomas
(that is where the EE install lives, and where the sites index.php file is.
Local Root: /Applications/MAMP/htdocs/thomas
EE is set up this way:
Template files are saved to: /Applications/MAMP/htdocs/thomas/system/template_files/
and EE creates folders inside that folder for each template group, e.g. “Weblog” and so on ...
The .htaccess file is placed in: /Applications/MAMP/htdocs/thomas/system/template_files/
So guys, how many errors have I made, and what do I need to correct, to get previews working with a MAMP install ... can it even be done? Oh, by the way, the MAMP server IS started, something I often forget