i believe it is possible (and i can say more: it's easy to make) that user in
away mode can be piked up by mode char just like op (@) or voice (+)... as i can uderstand, mIRC gets /who #channel to see modes of users... so:
#Olivka Azure H@ ~user@ns.fast.net.ua :0 user
#Olivka Olivka H@ [email]Olivka@host102-32-25.maxnet[/email] :2 user
#olivka End of WHO list.
H - means that user is "here"
#Olivka Azure G+ ~user@ns.fast.net.ua :0 user
#Olivka Olivka H@ [email]Olivka@host102-32-25.maxnet[/email] :2 user
#olivka End of WHO list.
G - means that user is "gone"
So it will be cool that i can mark all away people with gray color in nicklist for example

i hope that feature will be soon avaliable in next versin of mIRC
P.S. XChat by default marks away people with gray color