Seems to be underway. I've heard that folk in Hartlepool and Bristol have been updated overnight. I don't have any details as to the plan, but the official pilot blog may have more details as the rollout progresses.
Update: Teesside (Stockton), Avon (Bristol) and Croydon all updated overnight, too. Spiderplant reports that there'll be no rollout plan published and that the rollout won't be completed by the 6th (contrary to reports elsewhere).