Cuba announced a new property law Thursday that promises to allow citizens and permanent residents to buy and sell real estate -- the most significant market-oriented change yet approved by the government of Raúl Castro, and one that will probably reshape Cuba's cities and conceptions of class.The new rules go into effect Nov. 10, according to Cuba's state-run newspaper, and while some of the fine print is still being written, the law published on Thursday amounts to a major break from decades of socialist housing. For the first time since the early days of the revolution, buyers and sellers will be allowed to set home prices and move when they want. Transactions of various kinds, including sales, trades and gifts to relatives by Cubans who are emigrating, will no longer be subject to government approval, the new law says.