HTC confirmed to Engadget that the update, which also brings HTC Sense 3.6, has appeared in Nordic countries, while Recombu notes that German site HTCinside.de has seen the update appearing on its Sensation XE.
So it would appear that the update is about to be made available everywhere. I've contacted HTC for confirmation on the Nordic update, and I'll let you know if I hear anything regarding an update in the UK.
I'd expect the update to appear a bit later if your HTC phone is tied to a network. Generally it's the SIM-free devices that are treated to the latest version first.
The update itself is reportedly pretty hefty at 297MB, so if you do see it appearing on your phone's screen, it might be an idea to connect to Wi-Fi before beginning the download.
In February, HTC confirmed that the HTC Sensation and Sensation XE would be getting Ice Cream Sandwich before the end of March, so assuming the update arrives in the UK soon, it will be on schedule. The Sensation XL update will follow, with the HTC Desire HD, Incredible S, Desire S and Evo 3D getting updated "later this year".
Samsung, meanwhile, recently teased Galaxy S2 owners with a 10 March date for the Android 4.0 update posted on an official website, only to claim via Twitter that the date was incorrect.
Are you happy to wait patiently for Ice Cream Sandwich? Or are manufacturers making us wait too long? Tell me in the comments, or on our Facebook wall.