Every box in the Status panel of his preferences is checked, including idle after 10 minutes of inactivity; set "Away" after 20 minutes; set "Away" when screen saver is activated.
Yet, at my end, Adium says he's online and reachable. A friend has noticed the same thing (so it's not just me).
What sorts of things could be causing Adium to think a user is available when there have been no keystrokes or mouse clicks for hours?