I'm not able to confirm it yet, but a source that has been very reliable in the past says Chuck has received a standard 13 episode pickup with an option for a back 9. Hardly a shocker if true, unless you were one of those definitively declaring it had zero chance for renewal. If that's you, please wait for confirmation before going into hiding!
Update: again, my understanding of the deal is that it's a standard 13+9 order (NBC has the option to order 9 more episodes, commonly referred to as a "back 9") and that indicates Chuck would be on the fall schedule. Last year (for the current season). Chuck was announced as a mid-season show to begin with last May and there was no "back 9" attached. Later its air date was pushed up to early January and NBC ordered six additional episodes.