This is what I found on the net regarding the castle construction:
"The next reported re-decoration of Cinderella Castle will occurr in late October and September of 2006. The decorations and gold trimmings will be taken down in late October. The new decorations and paint will go up in mid-Semptember. Specific details of the decorations have not yet been revealed."
From another site:
"In the Magic Kingdom: The decorations will be coming down off Cinderellas Castle. Work is scheduled to begin September 13th, and the castle will get a repainting between the 19th and 30th of September. Some additional refurbishment will take place October-December in preparation for the installation of the Royal Bedchamber. There may be scaffolding, and a crane will be parked during the day."