The problem with cloudfuse is that it doesn't support full Unix filesystem semantics (you can't set the date/time stamp on files/objects once they're uploaded, and iirc you can't set user/group permissions), and it doesn't support things like symlinks or hard links. It also fully caches everything to be written to the local disk before it uploads anything, and it doesn't do chunking for the content to be uploaded.
All that makes it pretty tough to use as an remote filesystem alternative.
S3ql would be a lot closer to a proper remote filesystem alternative, if I could get confirmation that it does actually support using Rackspace Cloud Files as a backend, either directly or indirectly through a compatibility layer.