Airbus have updated their plans on their planned A320 Production Line in China;
- They expect the first production model's to be completed by end of 2008
- Production of 4 frames per month by 2010
- Final assembly site to be chosen by June. For more detail refer to this A.net thread
They also have confirmed A320 series production increasing to 32 frames per month by 2007.
Not sure of the maximum capacity that Airbus can take their current production lines to for their A320 series. But if all goes according to plan by 2010 they will have a minimum monthly production capacity of 36 frames per month though I feel this would be greater by then IMO.