On Tuesday Bioware released Game Update 5.1 - Defend the Throne:

• Master Mode Chapters
• 5 new Uprisings
• Galactic Command Gearing Changes -- We know that the changes in 5.1 are just the start. We are looking into simplifying, making faster, and making more alt friendly the gearing in GC. We are also looking into making getting through Command Ranks faster.

Coming in April, Game Update 5.2 which will include:

• Brand new story arc on Iokath. The Empire and Republic are fighting over control of the planet and you, as the Alliance Commander will choose who to side with.
• Two returning Companions: Quinn and Elara.
• After completing Iokath's storyline, it opens up into a new daily area.
• Coming with Iokath is the first boss of a new Operation. Each subsequent boss will be released in the future with the entire Op being completely released this year.
• Bioware is planning to have a PTS for 5.2 in the next few weeks. More details to follow.

Highlights

New Chapter Difficulty - Master!Earn new Achievements with this new way to experience the Knights of the Fallen Empire and Knights of the Eternal Throne Chapters!
New Uprisings! Jump into the action with five new Uprisings across the galaxy!

• Trench Runner- Republic Loyalists under the command of General Amos Rike have displaced Alliance forces on Denova and seized control of the baradium mines. Efforts to reclaim the mines have been thwarted by Republic artillery bombarding the "no man's land" between the Alliance beach head and the central processing facility. But where an army fails, a small team could succeed in navigating the battlefield trenches and taking out the Republic defenses.
• Destroyer of Worlds- Jedi Master Adelade is trying to awaken a dangerous abomination that has hibernated beneath the surface of Makeb for millennia. No records exist of this monstrosity, known only as Gethul. But if the creature awakes, it may be strong enough to destabilize Makeb's core and obliterate the planet. Infiltrate the underground tunnel, secure the explosives and deliver the payload to Gethul's lair. Only then can you destroy the monstrosity and save Makeb from Adelade's deranged plan.
• Divided We Fall- Rogue Coruscant security agents are plotting a false flag operation. They intend to attack the Senate Tower and plant false evidence in the hopes of inciting the Republic to war against the Alliance. Intel has traced the mastermind behind the plan, Commander Kalin, a former Republic veteran to a hidden base inside the The Works on Coruscant's lower level.
• Landing Party- Deserters from the Zakuulan military were tracked to Rakata Prime. Under the leadership of the former Battalion Commander Tassar, they are building a new and improved Star Fortress. Infiltrate their surface camp and eliminate Commander Tassar before her operations threaten galactic security.
• Trial and Error- Working from a hidden space station lab, a rogue group of Republic scientists led by Doctor Alirra Semhess has developed an experimental adrenal. The adrenal, code named RS-33, radically augments a subject's strength and agility at the expense of mental faculties.
  Left unchecked, Doctor Semhess and her colleagues could mass-produce RS-33 and create an army of unstoppable abominations to wreak havoc across the galaxy.