Google developed "MacFUSE, a Mac OS X version of the popular FUSE (File System in User Space) mechanism, which was created for Linux and subsequently ported to FreeBSD. FUSE makes it possible to implement a very functional file system in a normal program rather than requiring a complex addition to the operating system."
An interesting application for FUSE is Gmail Filesystem, which uses Gmail to store files and lets you use the files as if they were on your computer.
It will be interesting to see if GDrive, Google's solution for online file storage, will use FUSE.
