One is under the guidance of Michael Bay, but not intended to air until 2014.
"Set up as a twenty-year prequel to Robert Louis Stevenson’s classic book Treasure Island, Black Sails will follow the adventures of cutthroat corsair Captain Flint and his crew of brutal buccaneers, whose plundering ways have led them to the brink of extinction. Flint’s fight for survival forces him to seek sanctuary on the debauched pirate paradise New Providence Island, a place defined by both its enlightened ideals and stunning brutality. On the journey, Flint will take on a young, fast-talking addition to his crew— one, John Silver."
The other one is under the creative direction of Gale Ann Hurd, and set to air on FX.
“I have been obsessed with pirates and Port Royal for years, and have a library of books on the subject. The real story of privateers and the politics of the era has never been explored on screen, and I’m excited to bring that world to life with the terrific team at GK-tv.”
Set in the late 17th century on the island of Jamaica, the series will chronicle the namesake port’s notorious rise as the “richest and wickedest city” in the new world, and as a self-governing safe haven for cutthroat pirates, corrupt politicians, and ruthless merchants."
(Both of these blurbs are taken from screenrant.com