According to sony:
|"Update content:||Enhanced the security of the body software"|
This has nothing to do with sound quality. You guys are only wishing and believing there is a difference to sound.
So Sony releases an update 1.1, their first update. Then very shortly after they magically discover untold improvements and deliver that goodness to it's customers, I think not. It was a block to prevent Geohot's Android root method. Read above.
I know the update content but it was improved :) Lucky
Or you think sound is not changed?