As far as I've found, Steam automatically sets the following status :
Away : Person is logged in but has not been using Steam for 10-15 minutes.
Snooze : Person is logged in but has not been using Steam for 2 hours.
Online : Person is using the Steam client right now. In-game is added to this if the person is also playing a game.
Last Online : x hours ago : Person has logged out of Steam for the last x hours.
Please correct me if that's wrong. My question is, if someone's Steam status is online, does that mean they are currently using the Steam client, or that they are just logged in (Steam is in their computer's system tray next to the clock) ?