If you run the AppleScript:
tell application "iChat"
set status message to "testing"
set status to away
end tell
You might expect to have the away message “testing”. But what you get is an empty away message. That’s because set status destroys your status message. It behaves as if you had selected “Away”, “Available”, etc. as your status from iChat’s status menu.
If you want to set a custom away message, call set status first, so it won’t over-write your message.
tell application "iChat"
set status to away
set status message to "testing"
end tell
Filled as radar://6505882, but Apple considers it expected behavior.