Even though HTC has already said that the handset would "most likely" be getting updated to Android 2.2 (Froyo), there's nothing like a tweet from Sprint to confirm it. No date has been given for when we can expect to see the update, but the source code was only released a few days ago and I assume some wrinkles need to be ironed out because of the Sense UI, so we'll need to give it some time.
Oh, and there's talk that Sprint could be rolling out a maintenance update for the EVO on June 28th to fix a few issues, so don't get too excited if you get a notification about a new update being available that day.
Thanks, Tarjay!
