Which other IRC client implemented that? There's no notification of when someone sets themelves away or back so the only way for a client to tell is to continuously 'ask' the server using /who requests. Besides being messy, it'd also be a very considerable -and most likely unwelcome- drain on any IRC server if 95% of the users suddenly stat sending /who requests for every channel they're on every few seconds.
The only way that such a thing would become feasible is if it were implemented on the server side via some kind of notification of changes in a user's status.
I think it was Chatzilla, but XChat has the away feature as well, if I am not mistaken. They have some pretty cool features that would be cool to have in mIRC like making links look like links, and when a person talks for more than one line the nick is not repeated on each line, just the first. Also a status bar that shows IP addresses when you point at a nick, etc., etc.
I am not sure how the away thing works, regarding your
/who point, but it works and I doubt it would have been put into an IRC client if it would be an inconvenience, but I could be wrong.
