The Virtuous team have been hard at work and been able to successfully port the leaked HTC Endeavour RUU (0.96.401.2) to the HTC Sensation. While it is based on a developer RUU, it should be used with caution and is not suggested as a daily/production ROM. But if you want a first look at what Sense 4 looks like without having to wait, then it's worth a flash to your Sensation.
Screenshots from the XDA Thread:
You can download and get support from the XDA thread located here. By the way, Build 3 is coming soon by the looks of the post on the thread.