Agreed. I've been missing this since AIM went bust.

I also wish there were a way for me to send a low-priority message to my wife so that it didn't notify her regardless of her notification settings. We send each other news articles throughout the day but don't really want to interrupt each other. It would be great if there were a sender-side option that could enable this.

I've thought about using a shared document in the Notes app, or just use a different messaging app for low-priority stuff, but it seems like too much overhead. Does anyone else have a way of handling this?