As reported by Engadget Mobile:

Sprint’s ACE smartphone from Samsung has now been gifted with a luxurious Windows Mobile 6.1 upgrade. Sprint is really playing it up, too, touting that it’s bringing an “Enhanced Time-Saving Mobile Experience” to the phone — and to be fair, it’s also allowing the installation of unsigned apps and adding support for turn-by-turn navigation, so we suppose it’s a little more than just your run-of-the-mill 6.1 update.

For more information on installing the upgrade, visit the Samsung site here.