This should be true, and it is set to false because hal didn't match it with existent partition, the current version of hal in feisty don't support volume mounted with fuse.
This feature was added long time ago in git (but there were no stable relase since that time), and the edgy version of hal was patched to get it, but it seems that the patch has been droped.
Ok, that's what i expected :
mount : by-uuid/ 50F0A0A4F0A0923 0 on /media/sda1 type fuse (rw,nosuid, nodev,noatime, allow_other)
/dev/disk/
lshal : op/Hal/ devices/ volume_ uuid_50F0A0A4F0 A09230'
udi = '/org/freedeskt
[...]
volume.is_mounted = false (bool)
[...]
This should be true, and it is set to false because hal didn't match it with existent partition, the current version of hal in feisty don't support volume mounted with fuse.
This feature was added long time ago in git (but there were no stable relase since that time), and the edgy version of hal was patched to get it, but it seems that the patch has been droped.
I'll reopen the old bug.
Thanks for your report