I was reading this morning that they fixed the Jabba sequence in ANH (IV). They used The Phantom Menace CG Jabba in its stead.
And Gredo still shoots first, but they revisited the scene, made Han's movements more fluid, and it appeaers that they shoot at the same time.
(SIDE NOTE) - Apparently, first agressors were supposed to all die in Lucas' vision of Star Wars. Initially, Han was going to die in Return of the Jedi - killed by a bounty hunter who catches up to him and kills him out of revenge. Then, after the character became so beloved, he changed his mind. It bothered him taht Han was the initial agressor in the cantina, so he changed it. Then, bam! Greedo shoots first becomes the rallying cry for Star Wars purists (of which I am not) and opponents of post facto tinkering.
In addition - you've probably heard rumors that Hayden Christiansen will appear in Ep. 6, next to Obi Wan. Well, it's true. They edited out the guy who plays the older Obi Wan and pasted Hayden's face onto his. George claims that you take the last form that you were in as a Jedi when you die - and since Anakin was Hayden (at 25 or so), the change was an obvious way to tie together the two trilogies.
OH, OH, also - Timuera Morrison - the actor who played Jango Fett - yeah, he redubbed all of Boba Fett's dialogue as well as every clone/storm trooper's dialogue too, for consistency.
