According to Thameslink Programme News, the first 12-carriage train service arrives in December 2011 calling at a new station at Blackfriars. Amongst the many improvements being carried out, passengers will also benefit from a new ticket hall at Farringdon.
A new station will open in December 2011 at West Hampstead which will ease congestion and boost capacity for increased use in the future. It will link to a new wider footbridge with lifts to all platforms that have themselves been lengthened to accommodate 50% longer 12-carriage trains.
Tony Wilson has sent us this link