HTC UK is rolling out Android 2.3.5 update for Desire S users in the country. Update also upgrades the existing HTC Sense 2.1 to 3.0, which was first seen in devices like Sensation.
Update is currently available for unlocked units as well as carrier versions of Vodafone, O2 and Orange. As the update is being rolled out in stages, it might take some time to reach your device. If you have already updated your phone, do let us know about the experience in comments.
There is still no word on the update roll-out for other countries, but we hope to see it very soon.

mine updated this morning, no problems as yet.
How do people with originally brandEd phones which they have had unlocked & use a different SIM get access to the update.? I have an unlocked silver t-mobile Desire S, using a 3 SIM.