NPR’s new chief operating officer is Mitch Praver, a new-media exec with top-level experience at National Geographic and Discovery Communications. He’ll take charge of the network’s daily operations. Since leaving NGS in 2004, Praver managed an AOL unit that integrated AOL Instant Messenger into the online service and most recently ran business development and sales for Hillcrest Labs, developer of the Freespace interface technology used in the Logitech Air Mouse. The appointment was announced today by CEO Ken Stern.