The custom interface was introduced earlier in the year and includes a number of aspects that can be tailored by the user. Most notable among the features is the lock screen, which allows for quick access to popular applications such the camera, e-mail, and phone.
Although these Sense 3.0 updates are designed for U.K.-only models at this point, we might safely assume that the U.S. counterparts get the same treatment. That being the case, we may look for the Droid Incredible 2 (Verizon) and Inspire 4G (AT&T) to pick up Sense 3.0 before too long.
While the custom UI might not be the same thing as a new version of Android, it does lend to an improved user experience. Personally, I'm happy to see HTC staying true to its commitments and working to update things on its end, even for "old" phones like these.