if you install network-manager on debian sid, and everything looks ok,
but you still don't see the panel applet, (and perhaps you see it when
you login as root) check to see if you are a member of the 'netdev'
Apparently, this is required. I don't remember doing this explicitly on
my laptop when i installed network-manager, but when i installed it for
my brother, it didn't work, and adding his user account to the 'netdev'
group seemed to solve the problem (I also added him to the 'root' group,
and i'm a member of the 'root' group on my computer too).