Pocket-Lint: HTC Sense 4.0 is the latest version of HTC's user interface, layered over the top of Android 4. It lands on the HTC One series, as seen the HTC One X reviewed here.
Sense 3.6, on the other hand, is something of a halfway house between "old Sense" and the newer cleaner Sense. If you're interested in HTC Sense 3.6, we gave it a thorough reviewing here when it landed on the HTC Sensation XE.
MobileBliss: Verizon has accidentally revealed the specs and price for the upcoming HTC Droid Incredible 4G
CrazRoid.com : Sprint has unleashed a powerhouse, announcing the HTC EVO 4G LTE. It’s an Ice Cream Sandwich device, much resembling the HTC One X, with a few welcome changes — including micro SDcard and Google Wallet support. Some might even say its better.
Engadget - Over the last year, HTC has established a reputation for fragmenting its proprietary Sense UI even within the same version of Android. Why, Gingerbread alone is the foundation for at least three different iterations (2.1, 3.0 and 3.5) of the firmware. The bump to Ice Cream Sandwich is no different, with legacy devices getting an update to Sense 3.6 and the One series (and presumably any future devices) benefiting from version 4.0.