(I guess I am just confusing) :P
The more I think about this, the more you see how there can be problems. I understand with those who are critical of this idea, it is probably not a simple feature to add to IRC. Hopefully there is a way somehow to implement this in the future instead of having to change your nick to show you are away and having a nick become italicized when idle for a certain time.
The problem is that it will likely need to be a server side feature and thus have to be offered through the IRCds, and there are many different ones used by all the different networks.
I also agree that there may be a server load issue if some people switching their status back and forth. But how different is that from say, already available modes such as +h, +i, +p, +x, or +R? Or even +v, +h, and +o? Maybe a new mode added for "away" like +A and showing on the nicklist with a second symbol such as ^ or whatever other symbol that is not taken.
So for example if you are a Channel Operator that is away your nick can have a @^ in front of it and the away nicks in a group can drop to the bottom of that group/level.
This would also add a feature IRC that mIRC does not support now, which is displaying two nick modes on the nicklist at once, such as a voiced nick (+v) that is away can look like +^Nickname on the nicklist. Also for a nick to be italicized on the nicklist.
Anyway, this is just an idea and this is probably not the place to get something like this implemented as a feature in IRC.
It was an interesting discussion anyhow, thank you all for the feedback. You brought some points I did not think of when I first posted this.