Karmic Koala

I (probably foolishly) bumped my spare machine (which has lately acted as a jukebox/CIFS server) to Ubuntu 9.10 “Karmic Koala” the day it was released, since the machine doesn’t do anything critical. For a point upgrade on a fixed release system, it was quite smooth, but I’ve discovered a weird bug with SMB and FUSE that I haven’t yet been able to find a solution to. The basic jist of the problem is that under 9.10 it seems to be impossible to share things stored on volumes mounted via FUSE over CIFS; it just throws permissions errors when clients try to connect, even if guest access is enabled. There are other reports of Samba issues after upgrading to Karmic.
I’m reasonably sure it’s some kind of permissions issue having to do with the combination of ntfs-3g/fuse (the drive it shares is a large NTFS-formatted external drive) and Samba in conflict, but I haven’t yet managed to track it down.
Other than that one minor regression, Karmic seems to be a nice clean incremental update; no amazing new features (at least that I care about), and no catastrophic performance regressions or other classic upgrade symptoms. The noticeable improvements are mostly the result of moving off of the obsolete branches of various pieces of software, so modern plugins and compatibility improvements are available.
I’ll update this post with a solution if and when I find a solution, discounting “Install a more predictably behaved OS” style solutions.