Version:           1.00 (using KDE 4.4.3) 
OS:                Linux

It may not be standard to protocols like AIM and ICQ, but Pidgin (formerly GAIM) alters messages received (and locally typed) that are prefixed with "/me" so that:

   /me types an action.

becomes

   Name types an action.

with whatever decoration goes with the Action MessageType.  Quite a few of my buddies have used this feature thinking that my client, Kopete, would support it as well (probably out of habit, really).

It appears that someone wrote a plugin for the KDE 3.5.x series to do exactly this, but the devs weren't keen on having a plugin for just this one function and the author didn't want to develop a patch for the KDE 4 environment.

http://www.mail-archive.com/kopete-devel@kde.org/msg11266.html

But I do know that at least the Action MessageType is there to be exploited, because Kopete supports IRC and also because of this:

http://kopete.kde.org/chatwindowstyleguide/index.html

Incoming/Action.html, Outgoing/Action.html (Optional) (Kopete Extension)

   This template is a Kopete extension to the Adium format. It is available for Incoming and Outgoing direction. Action messages are special message to tell we are doing a action. Example: "/me is installing Kopete" would be displayed as "DarkShock is installing Kopete". 

Reproducible: Didn't try