SMB is really interesting idea, I may be miss understanding it, but would that in theory enable us to browse a remote SMB directory from within a SilverStripe site? If so that opens up a wide range of possibilities in terms of Intranet applications, for example if a company wanted open up part of their file server as as part of an extranet (which we've had a number of requests for in the past).
It also brings up the bigger issue of other "file systems" - for example, some video based content which we stream for clients, we host on Streaming net , a mini Alkami service, other clients with lots of big files may want to host those files on the Amazon S3 service as the bandwidth and storage is cheaper than what can be offered by most web hosts.
So, in the future I'm guessing we'll need to deal with a number of "files" areas, beyond "files on your webserver"..
...another file based authentication protocol to think about is WebDAV.
Anyway, really excited by your work :-)