For the moment NFS exporting is supported on kernels versions >=
2.6.0.

You need to add an fsid=NNN option to /etc/exports to make exporting a
FUSE directory work.

You may get ESTALE (Stale NFS file handle) errors with this.  This is
because the current FUSE kernel API and the userspace library cannot
handle a situation where the kernel forgets about a dentry which is
still referenced by the remote NFS client.  This problem will be
addressed in a later version.