We’ve known this was coming for a long time, but now it’s official. The Star Wars saga will be re-released in 3D beginning with Episode I in 2012. Depending on how The Phantom Menace does in its re-release the remaining five movies will be released each year following. So Attack of the Clones will be 2013, Revenge of the Sith in 2014, A New Hope in 2015, The Empire Strikes Back in 2016, and Return of the Jedi in 2017. According to the Hollywood Reporter the current limited number of 3D screens is why they are waiting so long. Lucas wants them on as many screens as possible.
And yes, there are likely going to be more tweaks to the movies. We’ve known since at least 2005 when Episode III hit DVD that they have been planning to replaced the stoned Yoda puppet in The Phantom Menace with a CG version to more closely match the CG Yoda in Episodes II and III as well as the original puppet (since the CG model was based on that in the first place). Changes in the other five movies are up in the air, but don’t be surprised to see some.