HTC's Sensation series phones have already gotten upgraded to Android 4.0 in many places, but T-Mobile subscribers with the Sensation 4G won't be getting Ice Cream Sandwich until May or possibly later. In a forum post yesterday, a T-Mobile spokesperson confirmed that while he isn't sure when Android 4.0 will be coming, it definitely won't arrive in April. There weren't too many more specifics in the post, but he suggests that T-Mobile is still testing the update in order to avoid releasing a "buggy, rushed, or poorly tested" version.
HTC announced that it would be upgrading the Sensation 4G back in March; since then, T-Mobile has said that it will be releasing 4.0, but has been cagey about making official statements. Expectant owners should apparently hold tight until "early or mid-May," at which point more information may be forthcoming... or maybe not.