Nothing open-source, unfortunately. I originally wrote a Windows fuse-like filesystem driver that we used in our 1.x product line, but that was a lot of work to maintain and have since switched to CBFS https://www.eldos.com/cbfs/ - which I wrote a libfuse binding for that we directly mount through via ctypes. They are actually in the process of formally building out FUSE support for CBFS but it's not officially supported.
I wouldn't ship a loosely maintained open-source kernel driver to paying customers. You can get CBFS for less if you're an indie shop, but the don't directly publish the price anymore. Compared to spending a year writing a gross Windows filesystem driver or hiring somebody to do it CBFS is amazingly inexpensive.
