Left to right, Google G1 (HTC Dream)(3.2" screen), Samsung Galaxy S GT I9000(4" screen) and Samsung Galaxy S III GT I9300 (4.8" screen).
The G1 is running FROYO 2.2.1, the Galaxy S is running GINGERBREAD 2.3.6 and the Galaxy S III is running ICECREAMSANDWICH 4.0.4 . All are rooted and network unlocked.
I only picked the Galaxy S III up from T Mobile at 14:30 on Friday the 6th of July and by 09:30 on the Saturday it was Rooted, SIM unlocked and running the latest ICS version of Android. Would've been quicker but I went to the pub Friday night!
The Galaxy S III is fantastically fast look at the Quadrant score for it.
Go here for the Quadrant score for my Galaxy S after tweaking it some time ago, what a difference?
As you can see from the below screen shot the Galaxy S III is network unlocked.