Don't you just hate it when someone forgets to tell you that they
have to go by PalPad and they log off and yet it still tells you
that they are online? My suggestion is to maybe make that PalPad
more better when it tells you if they are online or not, maybe
something coming up saying "This user has disconnected/logged out"
but yet you can still type to them.
you can check their last performed action on their userpage, the
green online light goes out at 15 minutes when a user is idle
enough to go off the online radar
the only way i can see something like this being implemented is a
way for a user to toggle their palpad availability status to be
something like skype's: