This low end Android device features HTC's Sense UI and has the smallest screen on any Android device, calling the HTC Tattoo to be confirmed of getting Android 2.1

Kindly note we understand that now that a phone running Android OS 2.1 is available that you are excited to get an update for your Tattoo. We are still working hard to building Sense for this new version but we expect to have the upgrade finished and ready to go soon. Please understand that it takes time to customize any Android version to ensure you have the intuitive experience Sense provides, and we hope you can be patient for just a little while longer.

source: unwiredview