I’m trying to find a system that will allow me to use (and modify) a single shared file (ie: a stylesheet that is used on several different sites) without having to manually edit each copy of it.

Could I configure the GAE to do this in any way..? Was thinking a carefully crafted folder structure might be an option.

So could GAE roll out the modified file to multiple domains..?

Any ideas would be awesome. Or if someone knows of some type of SVN system they could point me to.