On a call just now Khoros agree to set the time-out to something longer. They were going to try to go do it right now, for the moment, I requested 8 hours. I think that seems like a reasonable time, they tend to like to log people out in order to keep webserver open sessions to a reasonable number.
I'm curious what other sites do, I remember in 2006, I think it was days. But not sure.
-eric