When is an announcement made about which shows have been picked up and will be on the schedule next fall?

Usually the middle of May.

If you would like to now what shows have been cancelled and what shows have been renewed visit

http://tvguidelive.com/update/renewals.html

Thanks for that link. I was looking for things like Good Morning Miami, etc.

What does indefinite hiatus mean? Like for NBC's Ed, which I thought did pretty well, it says indefinite hiatus.