LUFS is a hybrid userspace filesystem framework supporting many "exotic" filesystems (localfs, sshfs, ftpfs, httpfs, socketfs, freenetfs, and nutellafs) transparently for any application. It can be regarded as doing the same job as the VFS (virtual filesystem switch) in the kernel: it is a switch, distributing the filesystem calls to its supported filesystems. However, LUFS filesystems are implemented in userspace. This would be a drawback for local filesystems where the access speed is important, but proves to be a huge advantage for networked filesystems where the userland flexibility is most important.
