Minecraft update 1.5 is set to arrive in "early March," according to a Twitter update from Mojang developer Jens Bergensten. To be a bit more exact, Bergensten says the PC update will be live in "roughly two weeks," placing it near the week of March 11.
Known as the Redstone Update, version 1.5 will address the redstone ore, giving it variable signal strength in addition to a new capacitor block. The Redstone Update also fixes the south-east rule glitch.