I don’t use HTC Sense services but it’s something that comes with the phone and many people may. I received the following this morning:
HTCSense.com is undergoing a renovation to improve the services and value we deliver to customers like you.
Until the new services are ready, features previously available on HTCSense.com will be shutting down. If you have been using HTCSense.com to sync your Contacts, Messages, Footprints or Call History, you can download your data through April 30, 2012. After April 30, your data will no longer be accessible and will be deleted.
I imagine Footprints was a popular app for many people which seemed useful and was preinstalled in all HTC’s I’ve had (except my latest Sensation).