Technically all the Android powered devices capable of running of Android Gingerbread will be able to run Android 4.0 ICS but Practically all devices may not give an overall good user experience . So all the manufactures are reviewing ICS on their devices to check the user experience and will release the latest OS according to the results.

HTC's list of devices that will surely get ICS :
* HTC Sensation (XL,XE,Original)
* HTC EVO 3D
* HTC Incredible S
* HTC Desire HD
* HTC Flyer
* HTC Rhyme
* HTC Desire S

Update (1) : No ETA's as yet. But may take 2-4 months because of the integration of Sense UI. HTC is definitely making every effort to provide update to most of the phones. Testing is under process. Desire Z and Salsa is going out of the list ,usability issues.

Update (2) : The phones exclusively on carriers such as HTC Amaze 4G,Thunderbolt,etc. will receive the update late.

Update (3) : New devices,i.e,Released after May 2011 will receive the updates prior to the old phones like Desire HD .

Update (4) : Google officially throws out Nexus One out of ICS list .
I updated a new post earlier about this .Forgot to edit this one. Link: https://plus.google.com/105502178297258827378/posts/6ev33ch3xHi