There have been three editions of d20 Star Wars; as was noted, Saga Edition is the newest of these.
Saga Edition is basically what I expected D&D 4E to be ... before 4E came out. It streamlines the 3.x rules nicely, ditching saving throws in favor of Reflex/Fortitude/Will Defenses, consolidates the core classes, and introduces a new talent tree mechanic that's somewhere between a feat in 3E and a power in 4E.
Jedi remain powerful, perhaps a bit too powerful, but hey, that's Jedi right? The nice thing about Saga is that the other classes (scoundrel, soldier, noble, scout) aren't sidelined by the Jedi. They each have their own niches, and Saga retains a meaningful skill system (4E's went past "streamlining" to "gutting" IMHO).
My group enjoys it -- we'd been running D&D 3.x Greyhawk forever (well, 8 or 9 years, however long 3x was out) and 2E before that. Some of the guys in the campaign had been getting frustrated with the creakier aspects of 3x (such as the "Save vs. Do Nothing For 3 Hours" effects. We tried out 4E, but while some in the group liked it (namely those who were getting tired of 3E) the old guard, diehard Greyhawk fans hated it. With a passion.
So we decided to run Star Wars instead. We just completed a run of 13 sessions. We're taking some time off to do some playtests, but I expect we'll be running it through the fall.
The campaign web site is here:
http://kotor.griffcrier.com/We're still fleshing it out, but it gives you an idea of what we've been up to.
Ken